Percentages
Work out percentages, changes, increases and discounts
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What is Percentages?
With this calculator you can answer the most common percentage questions without remembering any formula: how much a percentage of something is, what percentage a part represents, or how much a price has gone up or down.
It also tells you what's left after applying a discount or an increase and what the original price was before a sale. Just fill in the blanks in each sentence.
How to use it
- Find the card that matches your question, for example “Percentage of an amount” or “Percentage change”.
- Enter the numbers in the blanks of the sentence.
- In “Increase or decrease” and “Value before the percentage”, choose whether to add or subtract.
- Read the result on the right and copy it in one click.
Advantages
- Five different calculations on one page, all at once.
- Instant results as you type, no calculate button needed.
- Shows whether a change is an increase or a decrease and the difference in units.
- Free, no sign-up and no ads.
Technical details
The formulas used are: X% of Y = X × Y / 100; part of the total = X / Y × 100 (undefined if Y = 0); percentage change = (final − initial) / |initial| × 100, so the sign indicates an increase or decrease and the initial value cannot be 0; increase or decrease = Y × (1 ± X / 100); and original value before applying a percentage = final / (1 ± X / 100), useful for undoing discounts or increases. Results are shown with up to four decimal places and copied with up to six. Both comma and period are accepted as decimal separators.
Frequently asked questions
How do I calculate a percentage of an amount?
Multiply the amount by the percentage and divide by 100. 15% of 200 is 200 × 15 / 100 = 30.
How do I calculate how much a price has increased in percent?
Subtract the initial price from the final one, divide by the initial price and multiply by 100. If it goes from €80 to €100, the increase is (100 − 80) / 80 × 100 = 25%.
How do I find the original price before a discount?
Divide the sale price by (1 − discount / 100). If you pay €80 with a 20% discount, the original price was 80 / 0.8 = €100.
Why doesn't a 20% increase followed by a 20% decrease give the same price?
Because the decrease is applied to the already increased price. €100 + 20% = €120, and €120 − 20% = €96.
What percentage is one number of another?
Divide the part by the total and multiply by 100. 30 out of 120 is 25%.
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