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Calculator Answers

Percent Yield Calculator

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

Percent yield is a stoichiometric metric that measures the efficiency of a chemical reaction, expressed as the ratio of the actual yield to the theoretical yield multiplied by one hundred. The actual yield is the quantity of product obtained from a laboratory experiment, whereas the theoretical yield is the maximum amount of product predicted by calculations. A percent yield calculator computes the reaction efficiency, actual yield, or theoretical yield. Chemist and students use this calculation to assess reaction success and identify experimental losses.

Pick what to solve for, enter the two known values, and the calculator returns the third using % yield = actual / theoretical x 100. Choose a unit (g, kg, mg, mol) and keep both yield values in that same unit.

See also: Percent Decrease Calculator, Percent Error Calculator, and Dividend Yield Calculator.

Quick Answer

Calculate the efficiency of a chemical reaction. Enter the actual yield and theoretical yield to find the percent yield.

Solve for

Yield unit

Use the same unit on both actual and theoretical sides.

g
g

Tip

Theoretical yield comes from stoichiometry on the balanced equation: identify the limiting reactant, convert to moles of product, then convert moles back to mass with the product's molar mass.

Result

Percent yield

85%

Formula% yield = actual / theoretical x 100 = 8.5 / 10 x 100 = 85%

Percent yield captures losses from transfer, side reactions, evaporation, and incomplete conversion. Above 100% usually indicates impurity or residual solvent in the product mass.

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Examples

Actual 8.5 g, theoretical 10 g

= 85%

Actual 12 g, theoretical 15 g

= 80%

Theoretical 25 g at 90%

actual = 22.5 g

Actual 0.18 mol at 60%

theoretical = 0.30 mol

How it works

Percent yield is a straight ratio with a factor of 100. The calculator solves for whichever of the three values you leave blank, and validates the inputs so you do not divide by zero.

Percent yield · % = actual / theoretical x 100

Theoretical yield is the maximum a balanced equation predicts from the limiting reactant. Actual yield is what you isolate and weigh.

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Frequently asked questions

Percent yield compares the actual amount of product obtained from a reaction to the theoretical maximum predicted by stoichiometry. It is a measure of how efficient the reaction was under the conditions used.

% yield = (actual yield / theoretical yield) x 100. Both yields must be in the same unit (grams, moles, etc.) for the ratio to be meaningful.

Identify the limiting reactant on the balanced equation, convert its mass to moles, use mole ratios to find moles of product, then convert back to mass with the product's molar mass.

Mathematically it can be greater than 100, but in practice that almost always means the product was wet, contained unreacted starting material, or was contaminated with a side product. Re-dry and re-weigh before drawing conclusions.

Real reactions lose product to transfer steps, side reactions, evaporation, incomplete reaction, and purification. A yield around 70 to 90 percent is common for many synthetic procedures.

Whatever unit you measured in, as long as both the actual and theoretical yields are in the same unit. Grams is the most common; moles works when you used mole-based stoichiometry directly.