Free Percentage Calculator

To calculate X% of Y, multiply Y by X and divide by 100. Example: 20% of 150 is 150 × 20 / 100 = 30. With this calculator, just enter the two numbers and the result appears in real time.

Percentage change is calculated with the formula: ((new - old) / old) × 100. If the old value is 80 and the new is 100, the change is ((100 - 80) / 80) × 100 = +25%. A negative value indicates a decrease.

To add X% to Y: multiply Y × (1 + X/100). Example: adding 20% tax to $100 = $100 × 1.20 = $120. To remove: Y × (1 - X/100). Removing 10% from $200 = $200 × 0.90 = $180.

If a rate goes from 10% to 15%, it increased by 5 percentage points but by 50% in terms of relative percentage change. Percentage points indicate the absolute difference between two values expressed as percentages.

To find what percentage X is of Y, divide X by Y and multiply by 100. Example: 30 is (30 / 150) × 100 = 20% of 150. This is useful for proportions, discounts, and market shares.

If you know the discounted price and the discount percentage, use the formula: Original price = Discounted price / (1 - discount/100). Example: if the price after a 20% discount is $72, the original price was 72 / (1 - 0.20) = 72 / 0.80 = $90. Use the “Find Original” mode to calculate this automatically.

Percentage change measures how much a value increased or decreased from an original value: ((new - old) / old) × 100. Percentage difference compares two values without treating either as the baseline: |A - B| / ((A + B) / 2) × 100. Use percentage difference when neither value is the “starting point”.