Average atomic weight: 1.00784–1.00811 u
| Isotope | Fraction | Atomic weight/u |
| 1 | 0.999885(70) | 1.00782503223(9) |
| 2 | 0.000115(70) | 2.01410177812(12) |
Atomic weights and isotopic compositions were obtained from NIST Database 144
H I (H -like): 1310 levels, 26635 lines (E1: 26635), transition probabilities for 26635 lines
(Atomic Line List v3.00b5)
