THE WORKBENCH / QUANTITATIVE CHEMISTRY
Reagent ratio
calculator.
Set the molar proportions. Enter one known amount. Calculate the quantities for every other reagent—without manually scaling a recipe.
One specified quantity → a consistent molar feed ratio.
STEP 01 / REAGENTS
Build your ratio.
Give each reagent a molar mass and a relative number of moles. Names are optional. Start with two; add up to six.
For example, equivalents of 1, 2, and 3 give a 1:2:3 molar ratio—not a 1:2:3 mass ratio.
STEP 02 / KNOWN QUANTITY
Choose your starting point.
Specify how much of one reagent you have or want to use. The other masses and mole amounts follow the entered proportions.
UNDER THE HOOD / THE CHEMISTRY
One basis. Any proportion.
The calculation first converts the known quantity into millimoles. It then multiplies that amount by the ratio of molar equivalents and converts the result back to mass.
n is amount in mmol, r is relative molar equivalents, and M is molar mass in g/mol. Numerically, g/mol = mg/mmol, so m is in mg.
Limitations and assumptions
Choosing a molar ratio does not establish a balanced chemical equation, limiting reagent, expected product composition, theoretical yield, or synthesis outcome. For salts, confirm the hydrate or solvate form. Purity corrections, stock solutions, and reagent lookup are not included in this version. Independent experimental verification is needed before using any quantities as part of a synthesis procedure.