Theoretical Yield Actual Yield and Percent Yield

General Chemistry • Chemical Reactions

Written by STEM Calculators Team Published October 18, 2025 Updated February 24, 2026

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Theoretical Yield, Actual Yield, and Percent Yield

After you balance the reaction, the coefficients act as mole ratios. Pick one reference reactant and a target product. Convert the reference mass to moles, use the coefficient ratio to get moles of the target product, convert to mass to obtain the theoretical yield, and finally compare with a measured actual yield to compute the percent yield.

Workflow

Balance the chemical equation.
Choose a reference reactant and convert its mass to moles.
Use the mole ratio (coefficients) to find moles of the chosen product.
Convert those moles to mass → the theoretical yield.
Use the measured mass of that product (the actual yield) to compute the percent yield.

Calculations

1) Moles from reference mass

\[ \begin{aligned} n_{\text{ref}} &= \frac{m_{\text{ref}}}{M_{\text{ref}}} \end{aligned} \]

2) Mole ratio to product moles

\[ \begin{aligned} n_{\text{prod}} &= n_{\text{ref}}\, \frac{\nu_{\text{prod}}}{\nu_{\text{ref}}} \end{aligned} \]

3) Theoretical mass of product

\[ \begin{aligned} m_{\text{theor}} &= n_{\text{prod}}\,M_{\text{prod}} \end{aligned} \]

4) Percent yield

\[ \begin{aligned} \%\ \text{yield} &= \frac{m_{\text{actual}}}{m_{\text{theor}}}\times 100\% \end{aligned} \]

Frequently Asked Questions

How do you calculate theoretical yield from a chemical equation?

Balance the equation, convert the given reactant mass to moles with n = m / M, use the coefficient ratio to find product moles, then convert product moles to grams with m = n x M.

What is the difference between theoretical yield and actual yield?

Theoretical yield is the maximum product mass predicted by stoichiometry for the given reactant amount. Actual yield is the product mass measured in the lab.

How is percent yield calculated?

Percent yield is computed as (m_actual / m_theor) x 100. Values below 100% indicate losses or incomplete reaction under real conditions.

Why does the equation need to be balanced before finding percent yield?

Balancing provides the correct stoichiometric coefficients, which are the mole ratios needed to convert from reactant moles to product moles. Without a balanced equation, theoretical yield would be incorrect.

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