Work out reduced prices, falling sales or weight loss as a percentage — or take a percentage off any number in one step.
How to use the Percentage Decrease Calculator
- 1 Choose "Decrease by %" or "Find % decrease".
- 2 Enter the original value and the percentage (or the new, lower value).
- 3 Read the result and the amount of the reduction.
Formula
New value = Original × (1 − Percent ÷ 100) % decrease = (Original − New) ÷ Original × 100
Worked examples
Input: 1,500 reduced by 12%
Result: 1,320
1,500 × 0.88 = 1,320
Input: From 90 kg to 81 kg
Result: 10%
(90 − 81) ÷ 90 × 100 = 10%
Decreases are not symmetrical
A 20% decrease followed by a 20% increase does not bring you back to the start: 100 → 80 → 96. To undo a decrease of d%, you need an increase of d ÷ (100 − d) × 100 percent — 25% in this example.
When is the result negative?
If the "new" value is larger than the original, the decrease is negative — in other words it is actually an increase. Use the percentage increase calculator for that case.
Frequently asked questions
How do I subtract 30% from a number?
Multiply by 0.70 (that is, 1 − 0.30). For example, 250 × 0.70 = 175.
Can a decrease be more than 100%?
Not for positive quantities — a 100% decrease already reaches zero.
What is the difference between percentage decrease and discount?
They are the same calculation; a discount is simply a percentage decrease applied to a price.
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