How to use the percentage calculator
- Pick the card that matches your question.
- Enter the numbers. Results update as you type, with the formula underneath.
- Use the copy button to grab the result.
Features
- Percent of a number (discounts, tax, tips)
- One number as a percentage of another (scores, shares, conversion rates)
- Percentage increase or decrease between two values
- Apply a percentage to a value in either direction
- Every result shows the exact formula used
The formulas
Percent means “per hundred”, so every calculation is a variation on dividing or multiplying by 100:
- X% of Y = Y × X ÷ 100. Example: 15% of 200 = 30.
- X as a percent of Y = X ÷ Y × 100. Example: 30 is 15% of 200.
- Change from A to B = (B − A) ÷ |A| × 100. Example: 200 → 250 is a 25% increase; 250 → 200 is a 20% decrease.
- Y increased by X% = Y × (1 + X ÷ 100); decreased by X% = Y × (1 − X ÷ 100).
Percentage points versus percent
If an interest rate rises from 5% to 7%, it has risen by 2 percentage points but by 40 percent (2 ÷ 5 × 100). News reports mix these up constantly. The percentage change card gives the second figure; subtract the two rates yourself for the first.