Percent Yield Calculator
Calculate percent yield, actual yield, or theoretical yield — solve the chemistry yield equation for whichever quantity you're missing.
Input
Output
| Metric | Value |
|---|---|
| No data yet | |
Guides
The Percent Yield Calculator solves for percent yield, actual yield, or theoretical yield — pick the quantity you're missing, supply the other two, and it derives the rest.
What is percent yield?
Percent yield measures how efficient a chemical reaction was in practice, compared to the maximum amount predicted by stoichiometry:
Percent Yield (%) = Actual Yield ÷ Theoretical Yield × 100- Actual yield is what you actually recovered from the reaction (measured on the balance, in the lab).
- Theoretical yield is the maximum possible amount, calculated from the balanced equation and the limiting reactant.
Both yields must be in the same unit — grams, moles, milliliters, whatever the reaction was measured in — since the ratio between them is what matters, not the unit itself.
How to use it
- Pick what you want to Solve For — Percent Yield, Actual Yield, or Theoretical Yield.
- Fill in the other two fields (whichever weren't hidden by your solve-for choice).
The calculator shows the solved value along with percent yield, actual yield, theoretical yield, and a qualitative efficiency rating, plus a short step-by-step derivation.
Example
A reaction with a theoretical yield of 50 g produces 45 g of actual product:
Percent Yield = 45 ÷ 50 × 100 = 90%That's a 90% yield — rated "Excellent" by this calculator.
Why is my percent yield over 100%?
A yield above 100% usually means the product still contains impurities (unreacted solvent, moisture, or a byproduct) that added extra mass, or there was a measurement error. It doesn't mean the reaction produced more matter than physically possible — check your actual-yield measurement and purification steps.
What efficiency ratings does this calculator use?
90%+ is "Excellent," 75–89% is "Good," 50–74% is "Fair," and below 50% is "Poor." These are common lab rules of thumb, not a formal standard — some reactions (multi-step syntheses, low-yield couplings) are considered successful at far lower percentages.
Privacy
All calculations run entirely in your browser. Your figures are never uploaded or stored.
Use it from code
From 3 credits per callREST API
curl -X POST https://api.iotools.cloud/v1/tool/percent-yield-calculator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"solveFor": "percent",
"actualYield": "45",
"theoreticalYield": "50",
"percentYield": "90"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `percent-yield-calculator` tool (Percent Yield Calculator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.