Percentage Calculator
Calculate percentages three ways: find what percent of a number is, percentage of a total, and percentage increase or decrease between any two values.
A percentage expresses a number as a fraction of 100. The word comes from the Latin “per centum” — meaning “by the hundred.”
The three core percentage formulas:
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Find what percentage A is of B: Percentage = (A / B) × 100
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Find a percentage of a number: Result = (Percentage / 100) × Number
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Find the original number when you know a percentage: Original = Result / (Percentage / 100)
Worked examples:
Example 1 — What percentage is 45 of 180? Percentage = (45 / 180) × 100 = 25%
Example 2 — What is 35% of 240? Result = (35 / 100) × 240 = 84
Example 3 — 60 is 15% of what number? Original = 60 / (15 / 100) = 60 / 0.15 = 400
Common uses:
- Discounts: a 20% off sale on a £150 item saves £30
- Tax: 20% VAT on £80 adds £16
- Test scores: getting 42 out of 56 questions right = 75%
- Interest rates: 5% annual interest on £10,000 = £500/year
- Tip calculation: 15% tip on a £65 bill = £9.75
Percentage vs percentage points: These are different. If interest rates rise from 2% to 3%, that is a 1 percentage point increase — but a 50% increase in the rate itself. This distinction matters in finance and statistics.
Quick mental maths tricks:
- 10% = move decimal one place left (£250 → £25)
- 5% = half of 10%
- 1% = divide by 100
- 25% = divide by 4
- 33% ≈ divide by 3
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.