Stoichiometry

These tools work out the "how much" from a chemical formula or equation. You can calculate molecular weight (molar mass), find the coefficients that balance a chemical equation by conservation of atoms, and balance redox half-reactions that involve a transfer of electrons.

Molecular Weight Calculator (Molar Mass)

Enter a chemical formula and get its molecular weight (molar mass), computed automatically from the atomic weight of every element it contains. Handles simple formulas like H2O, formulas with parentheses like Fe2(SO4)3,...

Chemical Equation Balancer (Coefficient Calculator)

Enter an unbalanced chemical equation like H2 + O2 -> H2O and instantly get the smallest positive integer coefficients that satisfy conservation of mass.

Redox Half-Reaction Balancer (Ion-Electron Method)

Enter an unbalanced redox half-reaction like MnO4- -> Mn2+ and this tool automatically balances it using the ion-electron (half-reaction) method, adding H+, H2O, OH-, and electrons (e-) as needed. Supports both acidic an...