Tools › Percentage Calculator
Percentage Calculator
Free online percentage calculator. Find X% of a number, what percent one number is of another, or the percentage increase or decrease between two values.
Use it from code
The same function is available as an API endpoint. Free tier: 200 calls per day without a key. Pro lifts the limit.
curl -X POST https://spincrus.uz/api/v1/tools/percentage-calculator \
-H "content-type: application/json" \
-H "x-api-key: YOUR_KEY" \
-d '{"mode":"percent-of","a":"15","b":"200"}'FAQ
How do I calculate X percent of a number?
Divide the percentage by 100 and multiply by the number. 15% of 200 = 15 / 100 × 200 = 30. Use the "percent-of" mode with 15 and 200.
How do I calculate percentage increase or decrease?
Subtract the old value from the new one, divide by the old value, and multiply by 100. Going from 80 to 100 is (100 − 80) / 80 × 100 = 25% increase. A negative result is a decrease. Use the "change" mode.
Why does percentage change from zero give an error?
The change is measured relative to the starting value, and dividing by zero is undefined. If the old value is 0, any new value is an infinite relative change, so the tool refuses instead of showing a misleading number.
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