  Quantity                                                       Value                 Uncertainty           Unit
-----------------------------------------------------------------------------------------------------------------------------
alpha particle mass                                         6.644 657 3450 e-27      0.000 000 0021 e-27      kg
alpha particle mass in u                                    4.001 506 179 129        0.000 000 000 062        u
alpha particle molar mass                                   4.001 506 1833 e-3       0.000 000 0012 e-3       kg mol^-1
alpha particle relative atomic mass                         4.001 506 179 129        0.000 000 000 062        
Angstrom star                                               1.000 014 95 e-10        0.000 000 90 e-10        m
atomic mass constant                                        1.660 539 068 92 e-27    0.000 000 000 52 e-27    kg
atomic mass unit-electron volt relationship                 9.314 941 0372 e8        0.000 000 0029 e8        eV
atomic mass unit-hartree relationship                       3.423 177 6922 e7        0.000 000 0011 e7        E_h
atomic mass unit-hertz relationship                         2.252 342 721 85 e23     0.000 000 000 70 e23     Hz
atomic mass unit-inverse meter relationship                 7.513 006 6209 e14       0.000 000 0023 e14       m^-1
atomic mass unit-joule relationship                         1.492 418 087 68 e-10    0.000 000 000 46 e-10    J
atomic mass unit-kelvin relationship                        1.080 954 020 67 e13     0.000 000 000 34 e13     K
atomic mass unit-kilogram relationship                      1.660 539 068 92 e-27    0.000 000 000 52 e-27    kg
atomic unit of 1st hyperpolarizability                      3.206 361 2996 e-53      0.000 000 0015 e-53      C^3 m^3 J^-2
atomic unit of 2nd hyperpolarizability                      6.235 379 9735 e-65      0.000 000 0039 e-65      C^4 m^4 J^-3
atomic unit of action                                       1.054 571 817... e-34    (exact)                  J s
atomic unit of charge                                       1.602 176 634 e-19       (exact)                  C
atomic unit of charge density                               1.081 202 386 77 e12     0.000 000 000 51 e12     C m^-3
atomic unit of current                                      6.623 618 237 5082 e-3   0.000 000 000 0072 e-3   A
atomic unit of electric dipole mom.                         8.478 353 6198 e-30      0.000 000 0013 e-30      C m
atomic unit of electric field                               5.142 206 751 12 e11     0.000 000 000 80 e11     V m^-1
atomic unit of electric field gradient                      9.717 362 4424 e21       0.000 000 0030 e21       V m^-2
atomic unit of electric polarizability                      1.648 777 272 12 e-41    0.000 000 000 51 e-41    C^2 m^2 J^-1
atomic unit of electric potential                           27.211 386 245 981       0.000 000 000 030        V
atomic unit of electric quadrupole mom.                     4.486 551 5185 e-40      0.000 000 0014 e-40      C m^2
atomic unit of energy                                       4.359 744 722 2060 e-18  0.000 000 000 0048 e-18  J
atomic unit of force                                        8.238 723 5038 e-8       0.000 000 0013 e-8       N
atomic unit of length                                       5.291 772 105 44 e-11    0.000 000 000 82 e-11    m
atomic unit of mag. dipole mom.                             1.854 802 013 15 e-23    0.000 000 000 58 e-23    J T^-1
atomic unit of mag. flux density                            2.350 517 570 77 e5      0.000 000 000 73 e5      T
atomic unit of magnetizability                              7.891 036 5794 e-29      0.000 000 0049 e-29      J T^-2
atomic unit of mass                                         9.109 383 7139 e-31      0.000 000 0028 e-31      kg
atomic unit of momentum                                     1.992 851 915 45 e-24    0.000 000 000 31 e-24    kg m s^-1
atomic unit of permittivity                                 1.112 650 056 20 e-10    0.000 000 000 17 e-10    F m^-1
atomic unit of time                                         2.418 884 326 5864 e-17  0.000 000 000 0026 e-17  s
atomic unit of velocity                                     2.187 691 262 16 e6      0.000 000 000 34 e6      m s^-1
Avogadro constant                                           6.022 140 76 e23         (exact)                  mol^-1
Bohr magneton                                               9.274 010 0657 e-24      0.000 000 0029 e-24      J T^-1
Bohr magneton in eV/T                                       5.788 381 7982 e-5       0.000 000 0018 e-5       eV T^-1
Bohr magneton in Hz/T                                       1.399 624 491 71 e10     0.000 000 000 44 e10     Hz T^-1
Bohr magneton in inverse meter per tesla                    46.686 447 719           0.000 000 015            m^-1 T^-1
Bohr magneton in K/T                                        0.671 713 814 72         0.000 000 000 21         K T^-1
Bohr radius                                                 5.291 772 105 44 e-11    0.000 000 000 82 e-11    m
Boltzmann constant                                          1.380 649 e-23           (exact)                  J K^-1
Boltzmann constant in eV/K                                  8.617 333 262... e-5     (exact)                  eV K^-1
Boltzmann constant in Hz/K                                  2.083 661 912... e10     (exact)                  Hz K^-1
Boltzmann constant in inverse meter per kelvin              69.503 480 04...         (exact)                  m^-1 K^-1
characteristic impedance of vacuum                          376.730 313 412          0.000 000 059            ohm
classical electron radius                                   2.817 940 3205 e-15      0.000 000 0013 e-15      m
Compton wavelength                                          2.426 310 235 38 e-12    0.000 000 000 76 e-12    m
conductance quantum                                         7.748 091 729... e-5     (exact)                  S
conventional value of ampere-90                             1.000 000 088 87...      (exact)                  A
conventional value of coulomb-90                            1.000 000 088 87...      (exact)                  C
conventional value of farad-90                              0.999 999 982 20...      (exact)                  F
conventional value of henry-90                              1.000 000 017 79...      (exact)                  H
conventional value of Josephson constant                    483 597.9 e9             (exact)                  Hz V^-1
conventional value of ohm-90                                1.000 000 017 79...      (exact)                  ohm
conventional value of volt-90                               1.000 000 106 66...      (exact)                  V
conventional value of von Klitzing constant                 25 812.807               (exact)                  ohm
conventional value of watt-90                               1.000 000 195 53...      (exact)                  W
Copper x unit                                               1.002 076 97 e-13        0.000 000 28 e-13        m
deuteron g factor                                           0.857 438 2335           0.000 000 0022           
deuteron mag. mom.                                          4.330 735 087 e-27       0.000 000 011 e-27       J T^-1
deuteron mass                                               3.343 583 7768 e-27      0.000 000 0010 e-27      kg
deuteron mass in u                                          2.013 553 212 544        0.000 000 000 015        u
deuteron molar mass                                         2.013 553 214 66 e-3     0.000 000 000 63 e-3     kg mol^-1
deuteron relative atomic mass                               2.013 553 212 544        0.000 000 000 015        
deuteron rms charge radius                                  2.127 78 e-15            0.000 27 e-15            m
electron charge to mass quotient                            -1.758 820 008 38 e11    0.000 000 000 55 e11     C kg^-1
electron g factor                                           -2.002 319 304 360 92    0.000 000 000 000 36     
electron mag. mom.                                          -9.284 764 6917 e-24     0.000 000 0029 e-24      J T^-1
electron mag. mom. anomaly                                  1.159 652 180 46 e-3     0.000 000 000 18 e-3      
electron mass                                               9.109 383 7139 e-31      0.000 000 0028 e-31      kg
electron mass in u                                          5.485 799 090 441 e-4    0.000 000 000 097 e-4    u
electron molar mass                                         5.485 799 0962 e-7       0.000 000 0017 e-7       kg mol^-1
electron relative atomic mass                               5.485 799 090 441 e-4    0.000 000 000 097 e-4      
electron volt                                               1.602 176 634 e-19       (exact)                  J
electron volt-atomic mass unit relationship                 1.073 544 100 83 e-9     0.000 000 000 33 e-9     u
electron volt-hartree relationship                          3.674 932 217 5665 e-2   0.000 000 000 0040 e-2   E_h
electron volt-hertz relationship                            2.417 989 242... e14     (exact)                  Hz
electron volt-inverse meter relationship                    8.065 543 937... e5      (exact)                  m^-1
electron volt-joule relationship                            1.602 176 634 e-19       (exact)                  J
electron volt-kelvin relationship                           1.160 451 812... e4      (exact)                  K
electron volt-kilogram relationship                         1.782 661 921... e-36    (exact)                  kg
elementary charge                                           1.602 176 634 e-19       (exact)                  C
elementary charge over h-bar                                1.519 267 447... e15     (exact)                  A J^-1
Faraday constant                                            96 485.332 12...         (exact)                  C mol^-1
Fermi coupling constant                                     1.166 3787 e-5           0.000 0006 e-5           GeV^-2
fine-structure constant                                     7.297 352 5643 e-3       0.000 000 0011 e-3       
first radiation constant                                    3.741 771 852... e-16    (exact)                  W m^2
first radiation constant for spectral radiance              1.191 042 972... e-16    (exact)                  W m^2 sr^-1
hartree-atomic mass unit relationship                       2.921 262 317 97 e-8     0.000 000 000 91 e-8     u
hartree-electron volt relationship                          27.211 386 245 981       0.000 000 000 030        eV
Hartree energy                                              4.359 744 722 2060 e-18  0.000 000 000 0048 e-18  J
Hartree energy in eV                                        27.211 386 245 981       0.000 000 000 030        eV
hartree-hertz relationship                                  6.579 683 920 4999 e15   0.000 000 000 0072 e15   Hz
hartree-inverse meter relationship                          2.194 746 313 6314 e7    0.000 000 000 0024 e7    m^-1
hartree-joule relationship                                  4.359 744 722 2060 e-18  0.000 000 000 0048 e-18  J
hartree-kelvin relationship                                 3.157 750 248 0398 e5    0.000 000 000 0034 e5    K
hartree-kilogram relationship                               4.850 870 209 5419 e-35  0.000 000 000 0053 e-35  kg
helion g factor                                             -4.255 250 6995          0.000 000 0034           
helion mag. mom.                                            -1.074 617 551 98 e-26   0.000 000 000 93 e-26    J T^-1
helion mass                                                 5.006 412 7862 e-27      0.000 000 0016 e-27      kg
helion mass in u                                            3.014 932 246 932        0.000 000 000 074        u
helion molar mass                                           3.014 932 250 10 e-3     0.000 000 000 94 e-3     kg mol^-1
helion relative atomic mass                                 3.014 932 246 932        0.000 000 000 074        
helion shielding shift                                      5.996 7029 e-5           0.000 0023 e-5           
hertz-atomic mass unit relationship                         4.439 821 6590 e-24      0.000 000 0014 e-24      u
hertz-electron volt relationship                            4.135 667 696... e-15    (exact)                  eV
hertz-hartree relationship                                  1.519 829 846 0574 e-16  0.000 000 000 0017 e-16  E_h
hertz-inverse meter relationship                            3.335 640 951... e-9     (exact)                  m^-1
hertz-joule relationship                                    6.626 070 15 e-34        (exact)                  J
hertz-kelvin relationship                                   4.799 243 073... e-11    (exact)                  K
hertz-kilogram relationship                                 7.372 497 323... e-51    (exact)                  kg
hyperfine transition frequency of Cs-133                    9 192 631 770            (exact)                  Hz
inverse fine-structure constant                             137.035 999 177          0.000 000 021            
inverse meter-atomic mass unit relationship                 1.331 025 048 24 e-15    0.000 000 000 41 e-15    u
inverse meter-electron volt relationship                    1.239 841 984... e-6     (exact)                  eV
inverse meter-hartree relationship                          4.556 335 252 9132 e-8   0.000 000 000 0050 e-8   E_h
inverse meter-hertz relationship                            299 792 458              (exact)                  Hz
inverse meter-joule relationship                            1.986 445 857... e-25    (exact)                  J
inverse meter-kelvin relationship                           1.438 776 877... e-2     (exact)                  K
inverse meter-kilogram relationship                         2.210 219 094... e-42    (exact)                  kg
inverse of conductance quantum                              12 906.403 72...         (exact)                  ohm
Josephson constant                                          483 597.848 4... e9      (exact)                  Hz V^-1
joule-atomic mass unit relationship                         6.700 535 2471 e9        0.000 000 0021 e9        u
joule-electron volt relationship                            6.241 509 074... e18     (exact)                  eV
joule-hartree relationship                                  2.293 712 278 3969 e17   0.000 000 000 0025 e17   E_h
joule-hertz relationship                                    1.509 190 179... e33     (exact)                  Hz
joule-inverse meter relationship                            5.034 116 567... e24     (exact)                  m^-1
joule-kelvin relationship                                   7.242 970 516... e22     (exact)                  K
joule-kilogram relationship                                 1.112 650 056... e-17    (exact)                  kg
kelvin-atomic mass unit relationship                        9.251 087 2884 e-14      0.000 000 0029 e-14      u
kelvin-electron volt relationship                           8.617 333 262... e-5     (exact)                  eV
kelvin-hartree relationship                                 3.166 811 563 4564 e-6   0.000 000 000 0035 e-6   E_h
kelvin-hertz relationship                                   2.083 661 912... e10     (exact)                  Hz
kelvin-inverse meter relationship                           69.503 480 04...         (exact)                  m^-1
kelvin-joule relationship                                   1.380 649 e-23           (exact)                  J
kelvin-kilogram relationship                                1.536 179 187... e-40    (exact)                  kg
kilogram-atomic mass unit relationship                      6.022 140 7537 e26       0.000 000 0019 e26       u
kilogram-electron volt relationship                         5.609 588 603... e35     (exact)                  eV
kilogram-hartree relationship                               2.061 485 788 7415 e34   0.000 000 000 0022 e34   E_h
kilogram-hertz relationship                                 1.356 392 489... e50     (exact)                  Hz
kilogram-inverse meter relationship                         4.524 438 335... e41     (exact)                  m^-1
kilogram-joule relationship                                 8.987 551 787... e16     (exact)                  J
kilogram-kelvin relationship                                6.509 657 260... e39     (exact)                  K
lattice parameter of silicon                                5.431 020 511 e-10       0.000 000 089 e-10       m
lattice spacing of ideal Si (220)                           1.920 155 716 e-10       0.000 000 032 e-10       m
Loschmidt constant (273.15 K, 100 kPa)                      2.651 645 804... e25     (exact)                  m^-3
Loschmidt constant (273.15 K, 101.325 kPa)                  2.686 780 111... e25     (exact)                  m^-3
luminous efficacy                                           683                      (exact)                  lm W^-1
mag. flux quantum                                           2.067 833 848... e-15    (exact)                  Wb
molar gas constant                                          8.314 462 618...         (exact)                  J mol^-1 K^-1
molar mass constant                                         1.000 000 001 05 e-3     0.000 000 000 31 e-3     kg mol^-1
molar mass of carbon-12                                     12.000 000 0126 e-3      0.000 000 0037 e-3       kg mol^-1
molar Planck constant                                       3.990 312 712... e-10    (exact)                  J Hz^-1 mol^-1
molar volume of ideal gas (273.15 K, 100 kPa)               22.710 954 64... e-3     (exact)                  m^3 mol^-1
molar volume of ideal gas (273.15 K, 101.325 kPa)           22.413 969 54... e-3     (exact)                  m^3 mol^-1
molar volume of silicon                                     1.205 883 199 e-5        0.000 000 060 e-5        m^3 mol^-1
Molybdenum x unit                                           1.002 099 52 e-13        0.000 000 53 e-13        m
muon Compton wavelength                                     1.173 444 110 e-14       0.000 000 026 e-14       m
muon g factor                                               -2.002 331 841 23        0.000 000 000 82         
muon mag. mom.                                              -4.490 448 30 e-26       0.000 000 10 e-26        J T^-1
muon mag. mom. anomaly                                      1.165 920 62 e-3         0.000 000 41 e-3         
muon mass                                                   1.883 531 627 e-28       0.000 000 042 e-28       kg
muon mass in u                                              0.113 428 9257           0.000 000 0025           u
muon molar mass                                             1.134 289 258 e-4        0.000 000 025 e-4        kg mol^-1
natural unit of action                                      1.054 571 817... e-34    (exact)                  J s
natural unit of action in eV s                              6.582 119 569... e-16    (exact)                  eV s
natural unit of energy                                      8.187 105 7880 e-14      0.000 000 0026 e-14      J
natural unit of energy in MeV                               0.510 998 950 69         0.000 000 000 16         MeV
natural unit of length                                      3.861 592 6744 e-13      0.000 000 0012 e-13      m
natural unit of mass                                        9.109 383 7139 e-31      0.000 000 0028 e-31      kg
natural unit of momentum                                    2.730 924 534 46 e-22    0.000 000 000 85 e-22    kg m s^-1
natural unit of momentum in MeV/c                           0.510 998 950 69         0.000 000 000 16         MeV/c
natural unit of time                                        1.288 088 666 44 e-21    0.000 000 000 40 e-21    s
natural unit of velocity                                    299 792 458              (exact)                  m s^-1
neutron Compton wavelength                                  1.319 590 903 82 e-15    0.000 000 000 67 e-15    m
neutron g factor                                            -3.826 085 52            0.000 000 90             
neutron mag. mom.                                           -9.662 3653 e-27         0.000 0023 e-27          J T^-1
neutron mass                                                1.674 927 500 56 e-27    0.000 000 000 85 e-27    kg
neutron mass in u                                           1.008 664 916 06         0.000 000 000 40         u
neutron molar mass                                          1.008 664 917 12 e-3     0.000 000 000 51 e-3     kg mol^-1
neutron-proton mass difference                              2.305 574 61 e-30        0.000 000 67 e-30        kg
neutron-proton mass difference in u                         1.388 449 48 e-3         0.000 000 40 e-3         u
neutron relative atomic mass                                1.008 664 916 06         0.000 000 000 40            
Newtonian constant of gravitation                           6.674 30 e-11            0.000 15 e-11            m^3 kg^-1 s^-2
Newtonian constant of gravitation over h-bar c              6.708 83 e-39            0.000 15 e-39            (GeV/c^2)^-2
nuclear magneton                                            5.050 783 7393 e-27      0.000 000 0016 e-27      J T^-1
nuclear magneton in eV/T                                    3.152 451 254 17 e-8     0.000 000 000 98 e-8     eV T^-1
nuclear magneton in inverse meter per tesla                 2.542 623 410 09 e-2     0.000 000 000 79 e-2     m^-1 T^-1
nuclear magneton in K/T                                     3.658 267 7706 e-4       0.000 000 0011 e-4       K T^-1
nuclear magneton in MHz/T                                   7.622 593 2188           0.000 000 0024           MHz T^-1
Planck constant                                             6.626 070 15 e-34        (exact)                  J Hz^-1
Planck constant in eV/Hz                                    4.135 667 696... e-15    (exact)                  eV Hz^-1
Planck length                                               1.616 255 e-35           0.000 018 e-35           m
Planck mass                                                 2.176 434 e-8            0.000 024 e-8            kg
Planck temperature                                          1.416 784 e32            0.000 016 e32            K
Planck time                                                 5.391 247 e-44           0.000 060 e-44           s
proton charge to mass quotient                              9.578 833 1430 e7        0.000 000 0030 e7        C kg^-1
proton Compton wavelength                                   1.321 409 853 60 e-15    0.000 000 000 41 e-15    m
proton g factor                                             5.585 694 6893           0.000 000 0016           
proton mag. mom.                                            1.410 606 795 45 e-26    0.000 000 000 60 e-26    J T^-1 
proton mag. shielding correction                            2.567 15 e-5             0.000 41 e-5             
proton mass                                                 1.672 621 925 95 e-27    0.000 000 000 52 e-27    kg
proton mass in u                                            1.007 276 466 5789       0.000 000 000 0083       u
proton molar mass                                           1.007 276 467 64 e-3     0.000 000 000 31 e-3     kg mol^-1
proton relative atomic mass                                 1.007 276 466 5789       0.000 000 000 0083       
proton rms charge radius                                    8.4075 e-16              0.0064 e-16              m
quantum of circulation                                      3.636 947 5467 e-4       0.000 000 0011 e-4       m^2 s^-1
quantum of circulation times 2                              7.273 895 0934 e-4       0.000 000 0023 e-4       m^2 s^-1
reduced Compton wavelength                                  3.861 592 6744 e-13      0.000 000 0012 e-13      m
reduced muon Compton wavelength                             1.867 594 306 e-15       0.000 000 042 e-15       m
reduced neutron Compton wavelength                          2.100 194 1520 e-16      0.000 000 0011 e-16      m
reduced Planck constant                                     1.054 571 817... e-34    (exact)                  J s
reduced Planck constant in eV s                             6.582 119 569... e-16    (exact)                  eV s
reduced Planck constant times c in MeV fm                   197.326 980 4...         (exact)                  MeV fm
reduced proton Compton wavelength                           2.103 089 100 51 e-16    0.000 000 000 66 e-16    m
reduced tau Compton wavelength                              1.110 538 e-16           0.000 075 e-16           m
Rydberg constant                                            10 973 731.568 157       0.000 012                m^-1
Rydberg constant times c in Hz                              3.289 841 960 2500 e15   0.000 000 000 0036 e15   Hz
Rydberg constant times hc in eV                             13.605 693 122 990       0.000 000 000 015        eV
Rydberg constant times hc in J                              2.179 872 361 1030 e-18  0.000 000 000 0024 e-18  J
Sackur-Tetrode constant (1 K, 100 kPa)                      -1.151 707 534 96        0.000 000 000 47         
Sackur-Tetrode constant (1 K, 101.325 kPa)                  -1.164 870 521 49        0.000 000 000 47         
second radiation constant                                   1.438 776 877... e-2     (exact)                  m K
shielded helion mag. mom.                                   -1.074 553 110 35 e-26   0.000 000 000 93 e-26    J T^-1    
shielded proton mag. mom.                                   1.410 570 5830 e-26      0.000 000 0058 e-26      J T^-1
shielding difference of d and p in HD                       1.987 70 e-8             0.000 10 e-8             
shielding difference of t and p in HT                       2.394 50 e-8             0.000 20 e-8             
speed of light in vacuum                                    299 792 458              (exact)                  m s^-1
standard acceleration of gravity                            9.806 65                 (exact)                  m s^-2
standard atmosphere                                         101 325                  (exact)                  Pa
standard-state pressure                                     100 000                  (exact)                  Pa
Stefan-Boltzmann constant                                   5.670 374 419... e-8     (exact)                  W m^-2 K^-4
tau Compton wavelength                                      6.977 71 e-16            0.000 47 e-16            m
tau mass                                                    3.167 54 e-27            0.000 21 e-27            kg
tau mass in u                                               1.907 54                 0.000 13                 u
tau molar mass                                              1.907 54 e-3             0.000 13 e-3             kg mol^-1
Thomson cross section                                       6.652 458 7051 e-29      0.000 000 0062 e-29      m^2
triton g factor                                             5.957 924 930            0.000 000 012            
triton mag. mom.                                            1.504 609 5178 e-26      0.000 000 0030 e-26      J T^-1
triton mass                                                 5.007 356 7512 e-27      0.000 000 0016 e-27      kg
triton mass in u                                            3.015 500 715 97         0.000 000 000 10         u
triton molar mass                                           3.015 500 719 13 e-3     0.000 000 000 94 e-3     kg mol^-1
triton relative atomic mass                                 3.015 500 715 97         0.000 000 000 10         
unified atomic mass unit                                    1.660 539 068 92 e-27    0.000 000 000 52 e-27    kg
vacuum electric permittivity                                8.854 187 8188 e-12      0.000 000 0014 e-12      F m^-1
vacuum mag. permeability                                    1.256 637 061 27 e-6     0.000 000 000 20 e-6     N A^-2
von Klitzing constant                                       25 812.807 45...         (exact)                  ohm
weak mixing angle                                           0.223 05                 0.000 23                 
Wien frequency displacement law constant                    5.878 925 757... e10     (exact)                  Hz K^-1
Wien wavelength displacement law constant                   2.897 771 955... e-3     (exact)                  m K