What Is a Percentage Calculator?
A percentage calculator solves the most common percent math problems instantly in your browser — no server, no data sent, no installation required.
The Five Modes
Mode 1 — What Is X% of Y?
Enter a percentage and a value to find the result. For example: what is 20% of 150? Answer: 30. Useful for calculating discounts, tax amounts, shares, or commission.
Mode 2 — X Is What Percent of Y?
Enter a part and a whole to find the percentage. For example: 25 out of 200 is 12.5%. Useful for grades, market share, or any ratio question.
Mode 3 — Percentage Change
Enter an original value and a new value to find the percentage increase or decrease. For example, going from 80 to 100 is a +25% increase; going from 100 to 80 is a −20% decrease.
Formula: ((new − original) ÷ original) × 100
Mode 4 — Increase / Discount
Apply a percentage markup or discount to a price. Choose Increase for markups, VAT, or surcharges; choose Discount for sales and coupons. The result and the applied formula are shown side by side.
Tip Calculator
Enter the bill amount and a tip percentage to instantly see the tip amount and total. Common tip rates are 10%, 15%, and 20%.
Percentage Formulas Quick Reference
| Question | Formula |
|---|---|
| What is X% of Y? | (X ÷ 100) × Y |
| X is what % of Y? | (X ÷ Y) × 100 |
| Change from A to B | ((B − A) ÷ A) × 100 |
| Increase by X% | Value × (1 + X ÷ 100) |
| Discount by X% | Value × (1 − X ÷ 100) |
Common Percentage Examples
- VAT at 19%: A price of €80 + 19% VAT = €95.20
- 10% discount on €119.99: €119.99 × 0.90 = €107.99
- Grade: Scored 42 out of 60 = 70%
- Growth: Revenue went from €1,000 to €1,200 = +20%
How Results Are Rounded
All results are rounded to two decimal places using standard mathematical rounding (half-up). This matches the behavior of most financial calculators and spreadsheet applications.
Privacy
All calculations run entirely in your browser. No values are sent to a server, stored, or tracked.