Percentage Calculator
Three percentage calculations in one tool. Choose the type of calculation, enter two numbers and the result appears instantly.
Results are estimates. Solvemis accepts no responsibility for the results obtained or for how they are used.
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How it works
How to use it
- Choose what you want to work out: X% of a value, what share one number is of another, or the change between two values.
- Enter the two numbers the way you usually write them, with a point for decimals.
- The result appears instantly. For changes, the sign shows whether it is an increase (+) or a decrease (−).
How it is calculated
One percent is one hundredth: 15% is 0.15. X% of Y is X ÷ 100 × Y; the share of X in Y is X ÷ Y × 100; the change from X to Y is always divided by the starting value.
Change = (Y − X) ÷ |X| × 100
Sources
- NIST Guide to the SI, Chapter 7, section 7.10.2 (Percent) — National Institute of Standards and Technology (NIST)
About this calculator
The three calculations
X% of Y: discounts, tips, commissions. 10% of R$450 is R$45.
Share of X in Y: 45 correct answers out of 60 is 75%.
Change from X to Y: from R$80 to R$92 is +15%. You always divide by the starting value.
A common mistake
Two 20% discounts in a row don’t make 40% but 36%: successive percentages multiply, they don’t add up.
Frequently asked questions
How do you work out X% of a value?
Divide the percentage by 100 and multiply by the value: 15% of 200 is 15 ÷ 100 × 200 = 30.
Updated October 1, 2026
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