How do I calculate X% of Y?

Multiply Y by X/100. Example: 15% of 200 = 200 × 0.15 = 30.

How is percent increase calculated?

Percent increase = ((new − old) / old) × 100. A negative result means a decrease.

Results show sensible precision for readability. Exact intermediate math still follows standard percentage formulas.

Calculator Tools

Percentage Calculator

Calculate percentages online: what is X% of Y, what percent is X of Y, and percent increase or decrease.

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About this tool

Percentage Calculator covers the everyday percent problems people actually search for: portions of totals, reverse percentages and relative change: with transparent arithmetic.

How to use

Choose the calculation type (percent of, reverse percent, or change).
Enter the numbers involved.
Read the result and optional formula breakdown.
Change inputs to compare scenarios instantly.

Features

Percent-of calculations
Reverse percentage (X is what % of Y)
Percent increase and decrease
Client-side, private math

Common use cases

Homework and study checks
Business share and margin math
Growth and decline comparisons

Supported formats

Numeric input

Privacy

This tool processes data in your browser. Your content is not uploaded to our servers.

Frequently asked questions

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