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Percent Yield Calculator

Find percent yield from actual and theoretical yield, the theoretical yield from the limiting reactant, or the actual yield from a percent.

Level: Grades 10–11

Printable worksheet

Percent Yield Calculator

Know the answer you need? Pick an input to work backward.

Inputs
Calculate

What you recovered. Use the same unit as the theoretical yield (grams, moles…).

Result

Percent yield

79.9334%

The reaction gave 79.93% of the theoretical yield.

Shortfall (theoretical − actual)
1.8075

See the step-by-step solution ↓

Step-by-step solution

  1. Divide what you recovered by the most you could have made, then multiply by 100 to get a percent

    percent yield=7.29.0075×100=79.933389%

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out how much of the possible product your reaction really gave you, as a percentage. Real reactions rarely deliver every gram that the balanced equation promises. Some starting material does not react, and side reactions make other products. Some product is also lost while filtering, washing and transferring. Percent yield measures how close you came: the amount you actually recovered as a percentage of the most you could have made.

This calculator works in three directions. It finds the percent yield from your actual and theoretical yields. It finds the theoretical yield from the moles of limiting reactant, the one that runs out first. For that it also uses the coefficients (the numbers in front of each substance in the balanced equation) and the product's molar mass (grams per mole). And it finds the actual yield you can expect from a known percent yield.

Where it's used

Why this math matters outside the classroom:

  • Chemical plants. Chemical plants track percent yield to see how much product is lost to side reactions and handling.
  • Lab reports. A student who expects 12.0 g of product and recovers 9.6 g reports a percent yield of 80%.
  • Multistep synthesis. Drug makers multiply the yields of each step, so four steps at 90% each give about 66% overall.
  • Limiting reactant. Students find the limiting reactant first, since it sets the theoretical yield that every percent is measured against.

How to use it

  1. Choose what to calculate: percent yield, theoretical yield, or actual yield.
  2. For percent or actual yield, enter the values in any unit you like (grams, kilograms, moles), using the same unit for both.
  3. For theoretical yield, enter the moles of the limiting reactant, the coefficients of that reactant and of the product from the balanced equation, and the product's molar mass. Optionally add the mass you recovered to get the percent yield as well.
  4. Read the result and the steps beneath it.

What the inputs mean

Actual yield
What you recovered. Use the same unit as the theoretical yield (grams, moles…).
Theoretical yield
The maximum amount of product that the limiting reactant could form if the reaction went to completion with no losses.
Moles of limiting reactant
The limiting reactant is the one that runs out first. To find it, divide the moles of each reactant by its coefficient; the smallest result marks the limiting reactant. Convert grams to moles with the grams to moles calculator first.
Coefficient of the limiting reactant
The number in front of the limiting reactant in the balanced equation. Fractions such as 0.5 are allowed.
Coefficient of the product
The number in front of the product you are interested in.
Actual yield, if you have it
Optional. Adds the percent yield.

Formula and method

percent yield = actual yield ÷ theoretical yield × 100
moles of product = moles of limiting reactant × (product coefficient ÷ reactant coefficient)
theoretical yield (g) = moles of product × molar mass of product
actual yield = percent yield ÷ 100 × theoretical yield

The coefficients of a balanced equation, the numbers in front of each substance, tell you how many moles react and form. Multiplying the limiting reactant's moles by that ratio gives the most product that can form. Molar mass then turns those moles into grams.

Percent yield is one amount divided by another. So the actual and theoretical yields can be in any unit, as long as both use the same one.

Worked example

In N2 + 3H2 → 2NH3, hydrogen is the limiting reactant and you start with 6 mol of it. You collect 51.2 g of ammonia (17.031 g/mol). What are the theoretical and percent yields?

  1. Mole ratio: 6 mol H2 × 2/3 = 4 mol NH3.
  2. Theoretical yield: 4 mol × 17.031 g/mol = 68.124 g.
  3. Percent yield: 51.2 ÷ 68.124 × 100 = 75.1571%.

Result: The theoretical yield is 68.124 g of ammonia, and recovering 51.2 g is a 75.1571% yield.

Understanding the result

Yields between about 70% and 90% are common for careful single-step reactions in teaching labs, so landing in that range is a solid result. Multi-step syntheses multiply their losses, so overall yields fall quickly.

A yield above 100% does not mean you made matter from nothing. It usually means the product is still wet, contains impurities or unreacted starting material, or the theoretical yield was calculated from the wrong reactant.

Assumptions and limitations

  • The equation is balanced and the limiting reactant has been identified correctly.
  • The reaction is assumed to go fully to completion for the theoretical yield, with no competing reactions.
  • The calculator does not identify the limiting reactant for you; compare each reactant's moles divided by its coefficient to find it.
  • Purity of the recovered product is not taken into account. A crude product weighed before drying can overstate the yield.
  • Equilibrium reactions may never reach the theoretical yield even under ideal conditions.

Frequently asked questions

What is the difference between theoretical and actual yield?

The theoretical yield is calculated from the balanced equation: the most product the limiting reactant can form. The actual yield is what you measure after the experiment. Percent yield compares the two.

Can percent yield be over 100%?

Mathematically yes, chemically it signals a problem. Common causes are leftover solvent or water in the product, impurities, or a mistake in the theoretical yield. The calculator shows a note when this happens.

Do I need to convert to grams?

Not for percent yield, as long as actual and theoretical yield use the same unit. Moles divided by moles or grams divided by grams give the same percentage.

How is percent yield different from percent error?

Percent yield compares what you made with the maximum possible. Percent error compares a measured value with an accepted value and looks at the size of the difference, regardless of direction.

How this calculator is checked

Method: Standard stoichiometry: mole ratio from balanced-equation coefficients; percent yield = actual/theoretical × 100. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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