Percentage Calculator
Adjust the inputs below. Results update as you type.
How it works
Percentage problems show up everywhere: discounts, tips, grades, fees, and growth rates. This calculator covers the common forms—finding X% of a number, asking what percent A is of B, and measuring percent change—plus reverse modes when you know the result and need the missing input.
“Percent” means per hundred. Finding 18% of 250 is 0.18 × 250. Asking what percent 45 is of 60 is (45 ÷ 60) × 100. Percent change from an old value to a new value is ((new − old) ÷ |old|) × 100; a drop from 80 to 60 is a 25% decrease, not a 20-point story told as percent without care.
Watch percentage points versus percent: a rate moving from 10% to 12% rose 2 percentage points but 20% relatively. For discounts stacked in sequence, order and whether each applies to the original or remaining price changes the final amount. Use the step output to verify classroom or spreadsheet work before you trust a single headline number.
Input guidance
- Name the baseline clearly before asking “percent of” or “percent change.”
- For discounts, know whether each percent applies to the original or remaining price.
- Do not confuse percentage points with relative percent change.
The formula
X% of Y = (X ÷ 100) × Y. What percent is A of B = (A ÷ B) × 100. Percent change = ((new − old) ÷ old) × 100.
Worked example
20% of 150 = 0.20 × 150 = 30. And 45 out of 60 is (45 ÷ 60) × 100 = 75%.
More examples to test
- What is 18% of 250? Then reverse: 45 is what percent of 60?
- Price falls from $80 to $60: compute percent decrease and contrast with a 20-point framing error.
How to interpret results
Use the matching mode for your question, then read the steps to confirm the baseline. Relative and point changes answer different questions.
When this can be inaccurate
Rounding mid-step and ambiguous baselines cause most disagreements between tools and classroom keys.
Change history
- July 2026: Reverse modes, percent vs percentage-point guidance, and step clarity expanded.
- June 2026: Percentage solvers reviewed.
Site-wide corrections also appear on the corrections log.
Build math and logic skills with guided lessons
Educational platform recommendation.
Frequently asked questions
How do I find a percentage of a number?+
Convert the percent to a decimal and multiply. 15% of 80 is 0.15 × 80 = 12.
How do I calculate percent change?+
Subtract the old value from the new, divide by the old, and multiply by 100. From 50 to 60 is (10 ÷ 50) × 100 = 20% increase.
What is the difference between percent and percentage points?+
Going from 10% to 12% is a 2 percentage-point rise but a 20% relative increase. The two are often confused.
Why did my “20% off then 10% off” not equal 30% off?+
Stacked discounts usually apply sequentially to the remaining price, so the combined effect is less than the sum of the percents.
Guided next steps
Want the full workflow? Use this calculator inside a step-by-step guide.
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