Use this when you know the percentage and want to find the actual value. Example: what is 20% of 500?
Use this to express one number as a share of another. Example: 45 out of 180 — what percentage is that?
See how much something increased or decreased between two values. Example: price went from $80 to $120.
Work backwards when you know the result and the percentage but not the original total. Example: 20% of what number equals 50?
Which calculator do I need?
Percentages show up everywhere — discounts, tax, test scores, salary raises — but the actual calculation depends on what you already know and what you're trying to find. Here's how each section works:
- What is X% of Y? — You know the percentage and the total. Example: a $200 item has a 25% discount. What's the discount amount?
- X is what % of Y? — You want to express one number as a share of another. Example: you scored 45 out of 60. What's your percentage?
- Percentage change — You want to see how much something grew or dropped. Example: salary went from $80,000 to $95,000 — what's the increase?
- Work backwards — You know the result and the percentage but not the original total. Example: 15% of something equals $75. What's the full amount?
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No need to hit a button. The math runs entirely in your browser — nothing is sent anywhere or stored.
Frequently Asked Questions
How do I calculate what percentage one number is of another?
Divide the first number by the second, then multiply by 100. Example: 45 out of 180 — (45 ÷ 180) × 100 = 25%. The 'X is what % of Y?' section does this automatically.
How do I calculate a percentage increase?
Subtract the old value from the new value, divide by the old value, then multiply by 100. Formula: ((new − old) ÷ old) × 100. A salary increase from $80,000 to $95,000 is ((95000 − 80000) ÷ 80000) × 100 = 18.75% increase.
What is the difference between percentage point and percent change?
A percentage point is an arithmetic difference between two percentages. If interest rates go from 2% to 5%, that's a 3 percentage point increase — but a 150% relative increase. Context determines which one is more meaningful: percentage points for absolute comparisons; percent change for relative comparisons.
How do I work backwards from a percentage to the original number?
Divide the known value by the percentage expressed as a decimal. Example: 15% of something equals $75. Original = 75 ÷ 0.15 = $500. The 'Work backwards' section automates this.
How do I add a percentage to a number (e.g. add VAT)?
Multiply the base by (1 + percentage/100). To add 20% VAT to £100: 100 × 1.20 = £120. To remove VAT from a VAT-inclusive price: divide by (1 + percentage/100). Example: £120 ÷ 1.20 = £100 ex-VAT.