ConstantID

What changed between CODATA 2018 and 2022

CODATA revises its recommended values every four years from all the measurements available. This page compares the 247 measured values present in both adjustments, computed from NIST's two files. A shift of 1 σ means the value moved by one standard uncertainty of the 2018 value.

Largest shifts

Constant20182022Shift
Shielding difference of d and p in HD2.0200(20) × 10−81.987 70(10) × 10−8−16.1 σ
Shielding difference of t and p in HT2.4140(20) × 10−82.394 50(20) × 10−8−9.8 σ
Deuteron mass in u2.013 553 212 745(40)2.013 553 212 544(15)−5.0 σ
Deuteron relative atomic mass2.013 553 212 745(40)2.013 553 212 544(15)−5.0 σ
Alpha particle mass energy equivalent in MeV3727.379 4066(11)3727.379 4118(12)+4.7 σ
Electron g factor−2.002 319 304 362 56(35)−2.002 319 304 360 92(36)+4.7 σ
Alpha particle molar mass4.001 506 1777(12) × 10−34.001 506 1833(12) × 10−3+4.7 σ
Molar mass constant0.999 999 999 65(30) × 10−31.000 000 001 05(31) × 10−3+4.7 σ
Molar mass of carbon-1211.999 999 9958(36) × 10−312.000 000 0126(37) × 10−3+4.7 σ
Sackur-Tetrode constant (1 K, 100 kPa)−1.151 707 537 06(45)−1.151 707 534 96(47)+4.7 σ
Alpha particle mass6.644 657 3357(20) × 10−276.644 657 3450(21) × 10−27+4.7 σ
Sackur-Tetrode constant (1 K, 101.325 kPa)−1.164 870 523 58(45)−1.164 870 521 49(47)+4.6 σ
Atomic mass constant energy equivalent in MeV931.494 102 42(28)931.494 103 72(29)+4.6 σ
Atomic mass constant1.660 539 066 60(50) × 10−271.660 539 068 92(52) × 10−27+4.6 σ
Unified atomic mass unit1.660 539 066 60(50) × 10−271.660 539 068 92(52) × 10−27+4.6 σ
Atomic mass constant energy equivalent1.492 418 085 60(45) × 10−101.492 418 087 68(46) × 10−10+4.6 σ
Vacuum electric permittivity8.854 187 8128(13) × 10−128.854 187 8188(14) × 10−12+4.6 σ
Alpha particle mass energy equivalent5.971 920 1914(18) × 10−105.971 920 1997(19) × 10−10+4.6 σ
Electron mass energy equivalent in MeV0.510 998 950 00(15)0.510 998 950 69(16)+4.6 σ
Natural unit of energy in MeV0.510 998 950 00(15)0.510 998 950 69(16)+4.6 σ
Natural unit of momentum in MeV/c0.510 998 950 00(15)0.510 998 950 69(16)+4.6 σ
Bohr magneton in eV/T5.788 381 8060(17) × 10−55.788 381 7982(18) × 10−5−4.6 σ
Atomic unit of force8.238 723 4983(12) × 10−88.238 723 5038(13) × 10−8+4.6 σ
Bohr magneton in inverse meter per tesla46.686 447 783(14)46.686 447 719(15)−4.6 σ
Electron magnetic moment anomaly1.159 652 181 28(18) × 10−31.159 652 180 46(18) × 10−3−4.6 σ
Electron magnetic moment to Bohr magneton ratio−1.001 159 652 181 28(18)−1.001 159 652 180 46(18)+4.6 σ
Atomic unit of electric field gradient9.717 362 4292(29) × 10219.717 362 4424(30) × 1021+4.6 σ
Bohr magneton in K/T0.671 713 815 63(20)0.671 713 814 72(21)−4.5 σ
Fine-structure constant7.297 352 5693(11) × 10−37.297 352 5643(11) × 10−3−4.5 σ
Nuclear magneton in K/T3.658 267 7756(11) × 10−43.658 267 7706(11) × 10−4−4.5 σ

Biggest gains in precision

ConstantRel. unc. 2018Rel. unc. 2022Improvement
Shielding difference of d and p in HD9.9 × 10−45.0 × 10−5× 19.7
Shielded helion magnetic moment to Bohr magneton ratio1.2 × 10−88.1 × 10−10× 14.9
Helion magnetic moment to Bohr magneton ratio1.2 × 10−88.1 × 10−10× 14.9
Shielded helion magnetic moment to nuclear magneton ratio1.2 × 10−88.0 × 10−10× 14.7
Helion magnetic moment to nuclear magneton ratio1.2 × 10−88.0 × 10−10× 14.7
Helion g factor1.2 × 10−88.0 × 10−10× 14.7
Electron to shielded helion magnetic moment ratio1.2 × 10−88.1 × 10−10× 14.3
Shielded helion magnetic moment1.2 × 10−88.7 × 10−10× 14.0
Helion magnetic moment1.2 × 10−88.7 × 10−10× 14.0
Shielded helion gyromagnetic ratio in MHz/T1.2 × 10−88.6 × 10−10× 13.6
Shielded helion to proton magnetic moment ratio1.2 × 10−88.7 × 10−10× 13.5
Shielded helion gyromagnetic ratio1.2 × 10−88.8 × 10−10× 13.3
Deuteron-proton mass ratio5.5 × 10−114.2 × 10−12× 13.1
Shielding difference of t and p in HT8.3 × 10−48.4 × 10−5× 9.9
Proton mass in u5.3 × 10−118.2 × 10−12× 6.4
Proton relative atomic mass5.3 × 10−118.2 × 10−12× 6.4
Helion shielding shift1.7 × 10−63.8 × 10−7× 4.3
Electron-proton mass ratio6.1 × 10−111.7 × 10−11× 3.5
Electron magnetic moment to nuclear magneton ratio6.0 × 10−111.7 × 10−11× 3.4
Proton-electron mass ratio6.0 × 10−111.7 × 10−11× 3.4

Uncertainty grew

For 99 values the 2022 uncertainty is larger than in 2018, usually because new data disagreed with old and CODATA widened the uncertainty to cover both.