Percentage Calculator
Four common percentage calculations, solved instantly
What is X% of Y?
X is what % of Y?
% Change (X → Y)
Add / Subtract %
Calculations run locally in your browser. Verify independently for financial or professional use.
What Is a Percentage Calculation?
A percentage expresses a number as a fraction of 100. This tool covers the common percentage problems people run into: finding what percent one number is of another, finding a percentage of a number, and calculating percentage increase or decrease.
How It’s Calculated
X is what % of Y: (X ÷ Y) × 100. X% of Y: (X ÷ 100) × Y. Percentage change: [(New Value − Old Value) ÷ Old Value] × 100.
Example
What is 25% of 80? → (25 ÷ 100) × 80 = 20. A price rising from $50 to $65: [(65−50) ÷ 50] × 100 = 30% increase.
Learn more: Percentage Increase and Decrease and Percentage Points vs Percentage Change
Percentage Points vs. Percentage Change
These two terms are often used interchangeably but mean different things, and mixing them up is one of the most common percentage mistakes. If a discount goes from 20% to 25%, that is a change of 5 percentage points — but expressed as a percentage change, it is a 25% increase (5 ÷ 20 × 100). News reports and financial statements sometimes blur this distinction, so when precision matters, such as interest rates, tax rates, or survey results, check which one is actually being reported.
A Note on Rounding
This calculator returns results to two decimal places for currency-style figures. For financial or scientific work where rounding error compounds across many calculations, carry extra decimal places through intermediate steps and round only the final result.
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FAQ
What’s the difference between percentage increase and percentage points? Percentage increase is relative (e.g., 50 → 65 is a 30% increase); percentage points measure the raw difference between two percentages (e.g., 40% → 55% is a 15 percentage-point increase, not 15%).
How do I calculate a percentage decrease? Use the same percentage-change formula — if the new value is lower than the old value, the result will be negative, indicating a decrease.
Can I calculate reverse percentages (find the original number)? Yes — if you know the result and the percentage applied, you can back-calculate the original value; enter the known values into the relevant field.
Why do percentages sometimes not add up to 100% in real data? Usually due to rounding, overlapping categories, or “don’t know/other” responses not being shown — common in survey and statistical data.
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Common Percentage Calculations
Quick answers to percentage questions people search for most — type your own numbers into the calculator above for an instant result.
- 10% of 100 = 10
- 20% of 50 = 10
- 15% of 200 = 30
- 25% of 80 = 20
- 5% of 1000 = 50
- 50% of 120 = 60
- 30% of 150 = 45
- 8% of 250 = 20