# Percentage calculator

> Work out a percentage of a number, what percent one number is of another, the percent increase or decrease, or a price after a discount or markup.

URL: https://tools.cuelark.com/percentage-calculator
Publisher: Cuelark Team (https://cuelark.com)
Updated: 2026-11-10
Price: free, no sign-up
Privacy: runs in the browser; files are not uploaded

Five everyday percentage questions in one place: A% of B, A as a percent of B, the percent change from A to B, and B plus or minus A% (markups and discounts).

## How to use it

1. Choose the question you want answered.
2. Enter A and B; the answer updates as you type.
3. Copy the result, or use a sample to see each kind.

## Details

- **A% of B:** B × A ÷ 100
- **A is what % of B:** A ÷ B × 100
- **% change:** (B − A) ÷ |A| × 100
- **Discount:** B × (1 − A ÷ 100)

## Questions

### How do I calculate a percentage increase?

Subtract the old value from the new one, divide by the old value and multiply by 100. From 80 to 100 is (100 − 80) ÷ 80 × 100 = 25%.

### Why is a 50% rise followed by a 50% fall not back to the start?

The fall is taken from the bigger number. 100 + 50% = 150, and 150 − 50% = 75. Percent changes multiply rather than add.

### How do I work out 20% off a price?

Choose 'B minus A%', put 20 in A and the price in B. $59.99 less 20% is $47.99 (rounded to cents).

### What's the difference between percent and percentage points?

Going from 4% to 5% is a rise of 1 percentage point but 25 percent. The calculator gives percent; subtract the two rates for points.

### Is what I type sent anywhere?

No. The calculation runs in this browser tab with the same code our MCP server uses. Nothing you type is sent to a server or saved, apart from settings like filing status, which stay in this browser.

### Can an AI agent use this?

Yes. The same function is a tool on our free MCP server at tools.cuelark.com/mcp, so ChatGPT, Claude or Cursor get exactly the answer this page shows. 'Copy MCP call' gives you the arguments.

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