${{\mathit e}}$ MASS INSPIRE search

The mass is known more precisely in u (atomic mass units) than in MeV. The conversion is: 1 u = 931.494 103 72(29) MeV/c${}^{2}$ (2022 CODATA value, MOHR 2025). The conversion error dominates the uncertainty of the masses given below.
S003M
VALUE (MeV) DOCUMENT ID TECN  COMMENT
$0.51099895069$ $\pm0.00000000016$
MOHR
2025
RVUE 2022 CODATA value
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.51099895000$ $\pm0.00000000015$
TIESINGA
2021
RVUE 2018 CODATA value
$0.5109989461$ $\pm0.0000000031$
MOHR
2016
RVUE 2014 CODATA value
$0.510998928$ $\pm0.000000011$
MOHR
2012
RVUE 2010 CODATA value
$0.510998910$ $\pm0.000000013$
MOHR
2008
RVUE 2006 CODATA value
$0.510998918$ $\pm0.000000044$
MOHR
2005
RVUE 2002 CODATA value
$0.510998901$ $\pm0.000000020$ 1, 2
BEIER
2002
CNTR Penning trap
$0.510998902$ $\pm0.000000021$
MOHR
1999
RVUE 1998 CODATA value
$0.510998903$ $\pm0.000000020$ 1, 3
FARNHAM
1995
CNTR Penning trap
$0.510998895$ $\pm0.000000024$ 1
COHEN
1987
RVUE 1986 CODATA value
$0.5110034$ $\pm0.0000014$
COHEN
1973
RVUE 1973 CODATA value
1  Converted to MeV using the 1998 CODATA value of the conversion constant, $931.494013$ $\pm0.000037$ MeV/u.
2  BEIER 2002 compares Larmor frequency of the electron bound in a ${}^{12}\mathrm {C}{}^{5+}$ ion with the cyclotron frequency of a single trapped ${}^{12}\mathrm {C}{}^{5+}$ ion.
3  FARNHAM 1995 compares cyclotron frequency of trapped electrons with that of a single trapped ${}^{12}\mathrm {C}{}^{6+}$ ion.
  References:
MOHR 2025
RMP 97 025002 CODATA Recommended Values of the Fundamental Physical Constants: 2022
TIESINGA 2021
RMP 93 025010 CODATA recommended values of the fundamental physical constants: 2018
MOHR 2016
RMP 88 035009 CODATA Recommended Values of the Fundamental Physical Constants: 2014
MOHR 2012
RMP 84 1527 CODATA Recommended Values of the Fundamental Physical Constants: 2010
MOHR 2008
RMP 80 633 CODATA Recomended Values of the Fundamental Physical Constants: 2006
MOHR 2005
RMP 77 1 NIST Constants
BEIER 2002
PRL 88 011603 New Determination of the Electron's Mass
MOHR 1999
JPCRD 28 1713 CODATA Recommended Values of the Fundamental Physical Constants: 1998;
Also
RMP 72 351 CODATA Recommended Values of the Fundamental Physical Constants: 1998
FARNHAM 1995
PRL 75 3598 Determination of the Electron's Atomic Mass and the Proton/Electron Mass Ratio via Penning Trap Mass Spectroscopy
COHEN 1987
RMP 59 1121 CODATA Fundamental Physical Constants 1986 Adjustments
COHEN 1973
JPCRD 2 664 Comment{CODATA}: The 1973 Least Squares Adjustment of the Fundamental Constants