Percentage Calculator
Three percentage tools in one: find X% of Y, reverse percentages, and percent increase or decrease — instantly.
What is X% of Y?
X is what percent of Y?
Percentage change
Percentages without the mental math
Percentages show up everywhere: sale discounts, tips, tax, grades, raises, investment returns, and body-fat readings. The arithmetic is simple in theory — it's all multiplication and division by 100 — but under time pressure it's easy to slip a decimal point. This free percentage calculator covers the three questions people actually ask: "What is X% of Y?", "X is what percent of Y?", and "By what percent did it change?"
Type any numbers and each answer updates live — no buttons to press, no page reloads. Use the first mode for discounts and tips ("what is 20% of 150?"), the second for scores and shares ("45 out of 180 is what percent?"), and the third for tracking growth or shrinkage over time ("sales went from 80 to 100 — that's a 25% increase"). Like every Utilo tool, it works offline-capable in your browser with no signup and no data collection.
How to use the percentage calculator
- Pick your question: percent-of, reverse percent, or percent change — each has its own section above.
- Type the numbers: results update instantly as you type; decimals are fine.
- Read the answer: percent change tells you "increase" or "decrease" automatically.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 20% of 150 is (20 × 150) ÷ 100 = 30. The calculator above does this instantly.
How do I find what percent one number is of another?
Divide the first number by the second and multiply by 100. For example: 45 is what percent of 180? (45 ÷ 180) × 100 = 25%.
How do you calculate percentage increase or decrease?
Subtract the old value from the new value, divide by the old value, and multiply by 100. A positive result is an increase; a negative result is a decrease.
Is this percentage calculator free?
Yes — completely free, with no signup and no limits. All calculations happen in your browser.