# Percent Yield Calculator

Calculate percent yield from actual and theoretical yield. Also solve for actual or theoretical yield given the other two values.

## What this calculates

Calculate percent yield to see how efficient your chemical reaction was. Enter the actual yield from your experiment and the theoretical yield from stoichiometry, and this calculator gives you the percentage plus an efficiency rating.

## Inputs

- **Solve For** — options: Percent Yield (%), Actual Yield (g), Theoretical Yield (g) — Select which value to calculate.
- **Actual Yield** (g) — min 0 — The mass of product you actually collected.
- **Theoretical Yield** (g) — min 0 — The maximum possible yield from stoichiometry.
- **Percent Yield** (%) — min 0, max 200 — The percent yield (used when solving for actual or theoretical yield).

## Outputs

- **Result** — The calculated value.
- **Unit** — formatted as text — Unit of the result.
- **Efficiency Rating** — formatted as text — Qualitative assessment of the yield.
- **Formula** — formatted as text — Step-by-step calculation.

## Details

Percent yield is the single most common way to report how well a reaction performed. It compares what you actually got to what you could have gotten under perfect conditions.

**The Formula**

% yield = (actual yield / theoretical yield) x 100

**Quick Example**

You ran a synthesis and collected 8 g of product. Stoichiometry says the maximum was 10 g.

% yield = (8 / 10) x 100 = 80%

That is a good yield for most organic reactions.

**Rearranged Forms**

- Actual yield = (% yield / 100) x theoretical yield
- Theoretical yield = (actual yield / % yield) x 100

**What Counts as a Good Yield?**

| Range | Rating | Typical Context |
|-------|--------|-----------------|
| 90%+ | Excellent | Simple inorganic reactions |
| 70-89% | Good | Many organic syntheses |
| 50-69% | Moderate | Multi-step reactions |
| <50% | Low | Complex natural product synthesis |

**Why Yields Fall Below 100%**

Side reactions consume reactants, products stick to glassware during transfer, purification steps like recrystallization always lose some product, and incomplete reactions leave unreacted starting material behind.

## Frequently Asked Questions

**Q: What is percent yield?**

A: Percent yield measures how efficient a chemical reaction was by comparing the actual product collected to the theoretical maximum. The formula is (actual yield / theoretical yield) x 100.

**Q: Can percent yield be over 100%?**

A: In theory, no. A value over 100% usually means the product contains impurities, residual solvent, or water that adds to its mass. It can also mean an error in the theoretical yield calculation.

**Q: How do I find the theoretical yield?**

A: Use stoichiometry: convert the limiting reagent mass to moles, apply the mole ratio from the balanced equation, and convert product moles back to grams. You can also use the theoretical yield calculator on this site.

**Q: Is 80% yield considered good?**

A: For most organic chemistry reactions, 80% is a good yield. Simple precipitation or acid-base reactions often reach 90%+, while complex multi-step syntheses might consider 50% acceptable for individual steps.

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Source: https://vastcalc.com/calculators/chemistry/percent-yield
Category: Chemistry
Last updated: 2026-04-08