Percentage calculator
The three percentage questions everyone actually asks, answered as you type, with the working written out under each answer.
Guide
How to use it
- Find the card that matches your question. Each is written as a plain sentence.
- Type your two numbers into the sentence. The answer appears on the tile as you type.
- Read the grey formula line if you want to repeat the calculation on paper.
- Working with prices or pay? The discount and increase pages are set up for exactly that.
Examples
Worked examples
20 ÷ 100 × 150 = 30. The same shape answers tips, deposits and VAT-style additions.
18 ÷ 24 × 100 = 75%. Part divided by whole, then times 100, works for any score or share.
(925 − 850) ÷ 850 × 100 = 8.82% increase. The change is always measured against the old value.
Method
How it works
Per cent means per hundred, so every card is one line of arithmetic: percent of a number is (p ÷ 100) × n, what-percent is (part ÷ whole) × 100 and change is (new − old) ÷ old × 100. The formula line under each answer shows your numbers in that exact shape.
The calculations run in your browser as you type. Nothing is uploaded, and answers show up to four decimal places so rounding never surprises you.
FAQ
Frequently asked questions
How do I work out a percentage of a number?
Divide the percentage by 100 and multiply by the number. 20% of 150 is 20 divided by 100 times 150, which is 30.
How do I work out what percentage one number is of another?
Divide the part by the whole and multiply by 100. 40 out of 160 is 40 divided by 160 times 100, which is 25%.
How is percentage change calculated?
New value minus old value, divided by the old value, times 100. From 60 to 75 is a 25% increase. The old value is always the base. There is a dedicated change page with more examples.
Why is a 25% rise not undone by a 25% fall?
Because the base changes. 100 up 25% is 125, but 125 down 25% is 93.75. Percentage changes measure against their own starting point, so they are not symmetric.
What is a percentage point?
The simple difference between two percentages. A rate moving from 4% to 5% rises one percentage point, but that is a 25% relative increase. News reports mix these up constantly.
Does the calculator round?
Answers show up to four decimal places for small numbers and two for large ones. The formula line shows the exact calculation so you can carry full precision elsewhere.
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