Percentage Calculator
Three quick tools: percent of a number, percentage change, and discount price.
The three formulas
Percent of: X% of Y = Y × X ÷ 100. Percentage change: (B − A) ÷ A × 100 — positive means increase, negative means decrease. Discount: final price = P × (1 − D ÷ 100), and the saving is P × D ÷ 100. These three cover most daily situations: tips, exam marks, sales price tags and salary raises.
Formula used
% change = (B − A) ÷ |A| × 100. Discount price = P × (1 − D ÷ 100).
How to use this tool
- 1Pick which of the three calculations you need.
- 2Enter the two values for that calculation.
- 3Tap its Calculate button.
- 4Read the result in the receipt.
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 2,400 is 2,400 × 15 ÷ 100 = 360.
How is percentage change calculated?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase, negative is a decrease.
How do I work out a discounted price?
Multiply the price by the discount percent and divide by 100 to get the saving, then subtract that from the original price.