# Percentage Calculator

> Free percentage calculator with three modes: find X% of a number, work out what percent one number is of another, and calculate percentage increase or decrease.

Solve the three everyday percentage questions without a formula: what is 15% of 80, what percent is 12 of 48, and how much did a value go up or down. Everything runs in your browser.

*Interactive tool: enter your values at https://toollantern.win/percentage-calculator/ and results update instantly in your browser.*

## The three percentage formulas

Almost every percentage question is one of three shapes. This page solves all three side by side:

- **X% of Y** = Y × X ÷ 100. Use it for tips, discounts, tax and commission.

- **X as a percent of Y** = X ÷ Y × 100. Use it for test scores, budget shares and completion rates.

- **Percentage change** = (new − old) ÷ |old| × 100. A positive result is an increase, a negative result is a decrease.

## Worked examples

**15% of 80**: 80 × 15 ÷ 100 = **12**.

**12 out of 48**: 12 ÷ 48 × 100 = **25%**.

**50 to 65**: (65 − 50) ÷ 50 × 100 = **+30%**. Going back from 65 to 50 is only −23.08%, because the starting point is larger.

## Percent change vs percentage points

If an interest rate moves from 4% to 5%, it rose by **1 percentage point** but by **25 percent** in relative terms. News reports often mix the two. Use the third calculator for the relative change, and simple subtraction for percentage points.

## Common mistakes

A 20% drop followed by a 20% rise does not bring you back to the start: 100 becomes 80, then 96. Percentages always apply to the current base, so sequential changes multiply rather than add. To reverse a percentage increase, divide by (1 + rate) instead of subtracting the same percentage.

## Frequently asked questions
### How do I calculate a percentage of a number?

Multiply the number by the percentage and divide by 100. For example, 15% of 80 is 80 × 15 ÷ 100 = 12. The first calculator on this page does this for you.

### How do I work out what percent one number is of another?

Divide the part by the whole and multiply by 100. 12 out of 48 is 12 ÷ 48 × 100 = 25%.

### How is percentage increase calculated?

Subtract the old value from the new value, divide by the old value, and multiply by 100. Going from 50 to 65 is (65 − 50) ÷ 50 × 100 = 30%.

### Why is a 50% loss not undone by a 50% gain?

Because the second percentage applies to a smaller base. 100 minus 50% is 50, and 50 plus 50% is only 75. You would need a 100% gain to get back to 100.

### What is the difference between percent and percentage points?

Percentage points are the plain difference between two percentages (4% to 5% is 1 point). Percent change is the relative difference (4% to 5% is a 25% increase).

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Interactive version: https://toollantern.win/percentage-calculator/