This percentage calculator handles the three questions people ask most often: what a percentage of a number is, what percent one number is of another, and how much something has gone up or down in percentage terms. Results update as you type.
How to use it
Pick the box that matches your question and fill in both numbers. You do not need to type the % sign.
The formulas
X as % of Y = (X ÷ Y) × 100
% change = ((New − Old) ÷ Old) × 100
Worked examples
- Tip or tax: 15% of 200 = 0.15 × 200 = 30.
- Exam score: 30 out of 120 = 30 ÷ 120 × 100 = 25%.
- Price rise: from 80 to 100 = (100 − 80) ÷ 80 × 100 = 25% increase.
A common mistake
A 20% fall followed by a 20% rise does not bring you back to where you started. If a price drops from 100 to 80, it needs to rise by 25% to reach 100 again, because the second percentage is calculated on the smaller number. The percentage change box makes this easy to check.
Frequently asked questions
What is the difference between percent and percentage points?
If an interest rate moves from 4% to 5%, it has risen by one percentage point, but by 25 percent in relative terms. Use percentage points when comparing two percentages directly.
Can I use negative numbers or decimals?
Yes. All three calculators accept decimals and negative values.