Percentage Calculator

How to use this calculator

Enter your values after choosing the type of calculation in the tabs. The result updates as you type; press Calculate to confirm and jump to the result on mobile. Use Share to send the calculator with your result.

Percentage formulas

“Percent” means “per hundred”, so 15% is 15 ÷ 100 = 0.15.

Worked examples

• 15% of 200 = 0.15 × 200 = 30.
• 15 out of 20 as a percentage = 15 ÷ 20 × 100 = 75%.
• 30 is 15% of what? 30 ÷ 0.15 = 200.

Quick mental math

• 10% of a number: move the decimal point one place left (10% of 250 = 25).
• 5% is half of 10%; 20% is double 10%.
• Percent of is reversible: 8% of 50 equals 50% of 8 (both 4).

For increases and decreases use the Percent Change Calculator; to compare two values use Percentage Difference.

Frequently asked questions

About this tool

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Formula tests passed · human review pending

Last updated

31 Oct 2026

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