Percentage Calculator
Calculate percentages of amounts, percentage change, reverse percentages and more. Free percentage calculator for GCSE and IGCSE maths.
Find a Percentage of a Number
Calculate what X% of a number is
Enter values and click Calculate
Your result will appear here with step-by-step working
Percentage Essentials
Everything you need to learn percentages, broken down into simple, bite-sized cards.
1. What is a Percentage?
A percentage is a number out of 100. The word comes from per centum, meaning "out of one hundred". So means 45 out of 100.
Every percentage has a fraction and decimal twin: 45% = 45/100 = 0.45. Learning the common ones by heart (, , ) will save you loads of time in the exam!
2. How to Convert Fractions into Percentages?
To turn a fraction into a percentage, divide the top by the bottom, then multiply by 100. This works for any fraction.
3. How to Find a Percentage of a Number?
To find a percentage of a number, divide the percentage by 100 to write it as a decimal, then multiply by the number.
4. How to Find a Percentage Increase or Decrease?
To increase a value by a percentage, multiply by (1 + rate). To decrease, multiply by (1 - rate). Convert the percentage to a decimal first.
5. How to Calculate Percentage Change?
Percentage change compares an original value to a new value. To find it: subtract the original from the new, divide by the original, then multiply by 100.
6. How to Find a Reverse Percentage?
A reverse percentage finds the original value before a percentage change. If the price increased by , the multiplier is 1.20. To reverse it, divide by that multiplier.
To reverse a percentage, always divide by the multiplier. Never subtract the percentage from the new value!
Test Your Understanding
Try a quick question with ChatCat, your AI maths study buddy.
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Convert to a decimal: 0.15. Then multiply: .
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