Every Percentage Question in One Place

Discounts, tips, price changes, test scores, growth figures: percentages show up everywhere, and each question needs a slightly different formula. This page puts five small calculators side by side. Type into the sentence that matches your question and the answer updates as you type.

• Percent of a number: What is 20% of 150? (30)
• Percent ratio: 30 is what percent of 120? (25%)
• Percentage change: From 80 to 100 is a 25% increase.
• Increase / decrease: 200 increased by 15% is 230, decreased is 170.
• Percentage difference: The symmetric difference between two values, e.g. 40 and 60 differ by 40%.
• Copy button: Copy any result with one click.

The Formulas Behind It

Percent Of, Ratio and Increase / Decrease

X% of Y is Y × X / 100. To find what percent X is of Y, divide X by Y and multiply by 100. Increasing Y by X% gives Y × (1 + X / 100); decreasing it gives Y × (1 − X / 100).

Percentage Change vs. Percentage Difference

Percentage change has a direction: (new − old) / |old| × 100, so going from 80 to 100 is +25% but going from 100 to 80 is −20%. Percentage difference has none: |X − Y| divided by the average of the two values, times 100. Use change for "before and after" and difference when neither value is the starting point.

Frequently Asked Questions