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Percentage decrease calculator
Enter an amount and the percentage to take off, and get the new value and the difference. A second calculation gives the percentage decrease between two numbers.
- Free
- No sign-up
- Runs in your browser
What is X% of Y?
X is what percent of Y?
Percentage change from A to B
Increase or decrease an amount by a percentage
X is P% of what number?
100% private — the calculation is done in your browser and nothing is sent to any server.
Next step
Keep going with your result in another tool. Nothing is uploaded.
How it works
Read the answer
The result appears at the top of the list.
Check the formula
The formula is shown under each result.
How to decrease a number by a percentage
To decrease a number by a percentage, multiply it by 1 minus the percentage as a decimal. Reducing 80 by 25% is 80 × 0.75 = 60, a decrease of 20. In the calculator above, enter the amount and the percentage in the section increase or decrease an amount and choose decrease; the new value and the difference appear at the top of the results.
The formula
- New value = amount × (1 − percentage ÷ 100)
- Decrease = amount × percentage ÷ 100
- Percentage decrease between two values = (old − new) ÷ old × 100
A worked example, step by step
A shop lowers the price of a jacket from 80 by 25%. Step 1: turn 25% into a decimal, 0.25. Step 2: subtract it from 1, which gives 0.75. Step 3: multiply, 80 × 0.75 = 60. The new price is 60, which is 20 less than before. You can check it the other way: 20 ÷ 80 × 100 = 25%. If two discounts are applied one after the other, multiply the two factors instead of adding the percentages.
Examples
| Amount | Decrease | New value | Amount taken off |
|---|---|---|---|
| 50 | 10% | 45 | 5 |
| 80 | 25% | 60 | 20 |
| 200 | 15% | 170 | 30 |
| 1,200 | 3% | 1,164 | 36 |
| 35 | 50% | 17.5 | 17.5 |
Where you use it
- Sale prices and discounts, such as 20% off.
- Falling costs, weight loss and reductions in energy use.
- Working out how much a value dropped between two dates.
- Scaling recipes and quantities down.
Common mistakes
- A 100% decrease leaves zero, and a decrease cannot be more than 100%.
- A 50% decrease followed by a 50% increase does not return to the start: 100 falls to 50 and rises to 75.
- Percentage decrease is measured from the old value, so switching the two numbers gives a different percentage.
Private by design
The calculation runs in your browser as you type. The amounts you enter are never sent to a server, so you can use real prices, invoices and quotes.
Frequently asked questions
How do I calculate a 20% decrease?
Multiply by 0.8. For example, 150 × 0.8 = 120.
How do I find the percentage decrease between two numbers?
Subtract the new value from the old one, divide by the old value and multiply by 100. From 100 to 80: (100 − 80) ÷ 100 × 100 = 20%.
Is this the same as a discount calculator?
The maths is the same. For prices with a discount and savings, the discount calculator shows the final price and the amount saved directly.
Is this converter free?
Yes. There is no sign-up and no limit, and it runs in your browser, so nothing you type is sent to a server.
Does it work on a phone?
Yes. It works in any modern mobile browser, and the result updates as you type.
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