Molecular Mass Calculator

How to calculate the mass of a
particular isotopic composition

Enter the molecular formula of the molecule.
Examples: C6H12O6, PO4H2(CH2)12CH3

Standard Masses

Standard Formula Weight:   35.453000

Mono-isotopic molecular masses:
12C/14N:    57.9586223800
13C/14N:    57.9586223800
12C/15N:    57.9586223800
13C/15N:    57.9586223800

Calculate molecular mass by:

Molecular Mass for ClNa = 58.442308 Da

Charge = 0

23Na    22.989770

Average mass of this isotopic composition of Na: 22.989770 Da

35Cl    34.968853
37Cl    36.965903

Average mass of this isotopic composition of Cl: 35.452538 Da



Masses and Isotopic Compositions came from the NIST Physical Reference Data
*This mass was calculated from the distribution displayed in the text inputs.