Percent Yield Calculator
Actual over theoretical, and what a figure above 100 means.
Actual over theoretical, and what a figure above 100 means. Percent yield is actual over theoretical.
Percent yield
85.000%
good · 1.5 g unaccounted for
Percent yield is actual over theoretical. Losses come from incomplete reaction, competing side reactions, and simple mechanical transfer — product left on the filter paper and the glassware. Above 90% is excellent for most preparations, and synthetic routes with many steps compound their losses multiplicatively: five steps at 80% each leaves 33%.
How the Percent Yield Calculator works
Percent yield is actual over theoretical. Losses come from incomplete reaction, competing side reactions and simple mechanical transfer — product left on the filter paper and the glassware. A figure above 100% means something is wrong, not that something went well.
Also known as: percentage yield formula · theoretical yield calculator · reaction yield calculator · how to calculate percent yield
Where to go next
The Percent Yield question rarely arrives on its own. These are the ones that usually come with it:
- Molarity Calculator — Moles per litre of solution — not of solvent.
- Dilution Calculator — M₁V₁ = M₂V₂, with the diluent volume you actually need.
- Theoretical Yield Calculator — A yield over 100% means wet product, not a good day.
- Speed Distance Time Calculator — Any one of the three from the other two, in four units.
Frequently asked questions
How do I calculate percent yield?
Divide the actual yield by the theoretical yield and multiply by 100. Getting 8.5 g where 10 g was possible is 85%.
What does a yield above 100% mean?
An error, almost always. The product is usually still wet with solvent or contaminated with unreacted starting material. Dry to constant mass and weigh again.
What is a good percent yield?
Above 90% is excellent for a simple preparation, 70–90% is good, and below 40% suggests something worth investigating. Context matters — some reactions are inherently low-yielding.
Why do multi-step syntheses lose so much?
Because yields multiply rather than average. Five consecutive steps at 80% each leave 33% of what you started with, which is why route design favours fewer steps.
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Related calculators
Molarity Calculator
Moles per litre of solution — not of solvent.
OpenDilution Calculator
M₁V₁ = M₂V₂, with the diluent volume you actually need.
OpenTheoretical Yield Calculator
A yield over 100% means wet product, not a good day.
OpenSpeed Distance Time Calculator
Any one of the three from the other two, in four units.
Open