Molar Mass Calculator

Type a formula or a common compound name. The local chemistry engine understands nested groups, hydrates, charge notation and stoichiometric coefficients, then explains exactly how the molar mass is built.

Modern dataCIAAW 2024 abridged atomic weights.

Smart parserGroups, hydrates, charges, D/T and names.

Beyond massHill formula, DBE, mass % and atomic %.

PrivateNo upload, signup, API or external library.

Formula or compound name

Try “caffeine”, “sulfuric acid”, or a formula such as K₄[Fe(CN)₆].

CuSO₄·5H₂O

Supports (), [], {}, · / • / * hydrate separators, Unicode subscripts/superscript charges, common charge suffixes, D/T isotope symbols, and phase labels such as (aq), (s), (l), (g).

Mass ↔ moles converter

Mass (g)

Amount (mol)

Edit either field. The other updates using the molar mass of one formula unit, not a leading reaction coefficient.

Average molar mass

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g/mol

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Hill formula—

Unique elements—

Total atoms—

DBE / unsaturation—

Formula mass—

Particles in entered mol—

Percent composition by mass

Formula breakdown

Amount summary

Atomic-weight basis

Standard-weight values use the CIAAW 2024 abridged table. Elements without a standard atomic weight use a representative mass number and are explicitly flagged. D and T use isotope masses. This is an average molar-mass tool, not a monoisotopic mass-spectrum calculator.

Engine diagnostics · running…

Private by default. Formula parsing and conversions run locally in the browser.