How the Percentage Calculator Works

Calculate percentages, split tips and check discounts with worked formulas and examples. Free tools, localized numbers and no sign-up. Method and checked examples: (20 / 100) × 200 = 40. Percent of · What percent? · Percent change · Find the total · Increase/decrease.

Percent of · What percent? · Percent change · Find the total · Increase/decrease

What is X% of Y?

Enter a percentage and a number. The calculator multiplies the number by the percentage divided by 100. Formula: Result = (X / 100) × Y

Example: What is 15% of 200? → (15 / 100) × 200 = 30

X is what % of Y?

Enter a value and a total. The calculator divides the value by the total and multiplies by 100. Formula: Result = (X / Y) × 100

Example: 45 is what % of 180? → (45 / 180) × 100 = 25%

% Change from X to Y

Methodology: PercentEase divides by the absolute value of the starting amount. For a negative start, this is a stated convention, not a universal growth-rate definition: -100 to -50 gives +50%, while -100 to -150 gives -50%. Always report the original amounts alongside such a result. A zero starting value makes percentage change undefined, not infinite. The product formula for successive percentage changes assumes the usual multiplicative rates based on positive starting values; do not apply it blindly to the absolute-base convention across negative values. ((Y − X) / |X|) × 100

Example: % change from 80 to 100 → ((100 - 80) / 80) × 100 = 25%

Find the total

Known value ÷ (Known percentage (%) ÷ 100)

30 ÷ (20 ÷ 100) = 150

Increase/decrease

Original value × (1 ± Adjust by (%) ÷ 100)

100 × (1 + 20 ÷ 100) = 120

Tips for Accurate Calculations

✓ Always double-check which value is the 'part' and which is the 'whole'.
✓ Methodology: PercentEase divides by the absolute value of the starting amount. For a negative start, this is a stated convention, not a universal growth-rate definition: -100 to -50 gives +50%, while -100 to -150 gives -50%. Always report the original amounts alongside such a result. A zero starting value makes percentage change undefined, not infinite. The product formula for successive percentage changes assumes the usual multiplicative rates based on positive starting values; do not apply it blindly to the absolute-base convention across negative values.
✓ Negative percentage change indicates a decrease.
✓ You can use decimals in all input fields for precise calculations.