Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Molecular Weight Calculator

Compute the molecular weight (molar mass, g/mol) of a CHON-containing molecule from the number of carbon, hydrogen, oxygen, and nitrogen atoms in its formula, with an optional isotope-correction factor. Useful for routine stoichiometry on organic and biological molecules where C, H, O, and N dominate the elemental composition.

Carbon Atoms (C) (atoms)

Hydrogen Atoms (H) (atoms)

Oxygen Atoms (O) (atoms)

Nitrogen Atoms (N) (atoms)

Isotope Correction

Chemistry

Percent Composition Calculator

Find the mass percentage of any element in a compound. Essential for chemistry students and lab work when verifying empirical formulas or analyzing compound purity.

Mass of element (g)

Total molecular mass (g)

Key differences

	Molecular Weight Calculator	Percent Composition Calculator
Category	Chemistry	Chemistry
Inputs required	5	2
Result	Molecular Weight (g/mol)	Percent Composition (%)
What it does	Compute the molecular weight (molar mass, g/mol) of a CHON-containing molecule from the number of carbon, hydrogen, oxygen, and nitrogen atoms in its formula, with an optional isotope-correction factor. Useful for routine stoichiometry on organic and biological molecules where C, H, O, and N dominate the elemental composition.	Find the mass percentage of any element in a compound. Essential for chemistry students and lab work when verifying empirical formulas or analyzing compound purity.