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Yield % Calculator

Percent yield from actual vs theoretical, plus a quick theoretical-yield helper (limiting reagent × product MW ÷ reagent MW).

How to use this tool

Find out what fraction of the maximum possible product your reaction actually delivered. Enter what you isolated and what the reaction could give in theory; if you don't know the theoretical figure, the helper works it out from the limiting reagent.

What to enter

Actual yield: the mass of product you actually isolated, in grams.
Theoretical yield: the maximum mass the reaction could give, in grams. Don't know it? Use the helper below.
Compute theoretical (optional): enter the limiting reagent mass, its molar mass, the product MW and the stoichiometric ratio (moles product per mole reagent), then press Use as theoretical → to load the result into the theoretical field.

Reading the result

The headline is the percent yield, with a quality flag, excellent (≥ 90%), reasonable (≥ 70%), or low (with prompts to check for losses or side reactions). The helper's computed theoretical yield is shown alongside.

Worked example

An actual yield of 4.2 g against a 5.0 g theoretical maximum is 84%, a reasonable yield.

Yield

Actual yield

What you actually isolated and weighed after work-up and drying. Theoretical yield

The most you could get if every limiting-reagent molecule converted. Don't know it? Use the helper below.

Compute theoretical (optional)

Limiting reagent mass

Mass of the reagent that runs out first, it caps the yield. Limiting MW

g/mol

Molar mass of that limiting reagent. Product MW

g/mol

Molar mass of the product you're making. Stoichiometric ratio (prod / reagent)

Moles of product per mole of limiting reagent, from the balanced equation (often 1).

Result

Percent yield compares what you isolated against the theoretical maximum. 100% is the ceiling set by stoichiometry; most real reactions land lower, with losses from work-up, side-reactions, or incomplete conversion.

Methodology

Percent yield = (actual / theoretical) × 100. Theoretical yield from limiting reagent = (mass_lim / MW_lim) × ratio × MW_product.