Four percentage questions, one tool.
Of, share-of-total, difference, change. Type values; results update as you go.
What is X% of Y?
Find a percentage of a given value.
X is what % of Y?
Find the percentage one value represents of another.
% of
Percentage difference
Symmetric difference between two values, relative to their average.
Percentage change
Increase or decrease from a starting value to an ending value.
About
One tool covering the four most common percentage operations. Use it for sales-tax estimates, discount calculations, year-over-year change, or quick share-of-total comparisons.
All math is computed locally in your browser. Results are rounded to two decimals on display; the underlying calculation is full precision.
How to Use
- Pick the percentage card that matches your question.
- Type values into the two input boxes.
- Read the result instantly — no submit button needed.
- Repeat for the next calculation; values stay until you change them.
Formulas Used
The four cards use these formulas:
X / Y × 100 = X is what % of Y
|V1 − V2| / avg × 100 = percentage difference
(End − Start) / Start × 100 = percentage change
Example Calculation
Frequently asked questions.
Is this percentage calculator free?
Yes, Binary Lab's percentage calculator is completely free with no signup required.
What percentage operations does it support?
Four operations: what is X% of Y, X is what % of Y, percentage difference between two values, and percentage change from a starting to an ending value.
What is the difference between percentage difference and percentage change?
Percentage difference is symmetric — it uses the average of two values as the denominator. Percentage change is directional — it uses the starting value as the denominator and tells you increase or decrease.
Can I use it on mobile?
Yes. The calculator is fully responsive and works on any device with a browser.
How accurate is the result?
The math is full-precision; results are rounded to two decimals only for display. No rounding error in the underlying calculation.
Other calculators in the kit.
Working on something more complex?
If your math doesn't fit a percentage card, talk to us. We'll model it with you.
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