Percentage Calculator
The Percentage Calculator works out the three calculations people need most often: a percentage of a number, what percentage one number is of another, and percentage change. Enter your figures and the result is shown with the full working, so you can see exactly how it was reached.
Percentage Calculator
The interactive calculator will appear here. The page content, method and FAQs below are complete.
The formula behind the Percentage Calculator
To find a percentage of a number instead, reverse it: (Percentage ÷ 100) × Number. Both come from the same relationship - a percentage is simply a part expressed out of 100.
Worked examples
The clearest way to understand the Percentage Calculator is to see it used. Each example below works through the steps with real figures.
What is 15% of a £240 restaurant bill?
- Convert the percentage to a decimal: 15 ÷ 100 = 0.15
- Multiply by the number: 0.15 × £240 = £36
Answer: £36
A pupil scores 43 out of 60 on a test. What percentage is that?
- Divide the part by the whole: 43 ÷ 60 = 0.7167
- Multiply by 100: 0.7167 × 100 = 71.67%
Answer: 71.67%
A train fare rises from £12.40 to £13.80. What is the percentage increase?
- Find the difference: £13.80 − £12.40 = £1.40
- Divide by the original value: £1.40 ÷ £12.40 = 0.1129
- Multiply by 100: 0.1129 × 100 = 11.29%
Answer: 11.29% increase
Things worth knowing
X% of Y always equals Y% of X
Percentages are commutative. 8% of 50 is the same as 50% of 8 - both are 4. If a percentage looks awkward to work out in your head, flip it. 4% of 75 is hard; 75% of 4 is obviously 3.
Percentage and percentage points are not the same
If an interest rate moves from 10% to 15%, that is a rise of 5 percentage points, but a 50% relative increase ((5 ÷ 10) × 100). Both describe the identical change. Mixing the two up is one of the most common errors in financial reporting.
A rise then an equal fall does not cancel out
Increase £200 by 10% and you get £220. Decrease that by 10% and you get £198, not £200 - because the 10% fall applies to £220, not the original £200. Each percentage change works on the current value.
Percentages above 100% are valid
A 200% increase means a value has tripled. A salary rising from £30,000 to £90,000 is a 200% increase, not 300%. Negative percentages are valid too - they simply describe a fall.
Quick reference
| Percentage | Fraction | Decimal |
|---|---|---|
| 1% | 1/100 | 0.01 |
| 5% | 1/20 | 0.05 |
| 10% | 1/10 | 0.10 |
| 20% | 1/5 | 0.20 |
| 25% | 1/4 | 0.25 |
| 50% | 1/2 | 0.50 |
| 75% | 3/4 | 0.75 |
| 100% | 1 | 1.00 |
Our method
This page is maintained as a UK reference tool. The figures and formula behind it are checked against current official guidance, and the approach is set out plainly so you can see how a result is reached. If a rate changes - for example at a Budget or a new tax year - the page is updated and the review date below is refreshed.
Frequently asked questions
How do I work out a percentage of a number?
Divide the percentage by 100, then multiply by the number. For example, 30% of 250 is (30 ÷ 100) × 250 = 75. The calculator above does this and shows each step.
How do I find what percentage one number is of another?
Divide the first number by the second, then multiply by 100. 18 out of 40 is (18 ÷ 40) × 100 = 45%.
How do I calculate percentage increase or decrease?
Find the difference between the two values, divide it by the original value, then multiply by 100. If the new value is higher the result is an increase; if lower, a decrease.
Is "per cent" one word or two?
In formal UK English, "per cent" is two words in running text. "Percent" as one word is widely accepted, and the % symbol is standard in tables and data.
Can a percentage be more than 100%?
Yes. Percentages over 100% describe a value larger than the original whole - a 150% increase means something has more than doubled. This is mathematically correct and common in finance.
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