Percentage Decrease Calculator
Reduce any number by a percentage and see the new total, the amount removed and the percentage that remains.
How it works
Decreasing by a percentage multiplies by one minus that percentage as a decimal. A 15% cut is a multiplication by 0.85, so the result keeps 85% of the original.
Decreases do not cancel increases of the same percentage. A 50% rise followed by a 50% cut leaves you at 75% of where you started, because the cut applies to the larger figure. The same asymmetry means a 50% loss needs a 100% gain to recover.
The formula
New value
new = original × (1 − percent ÷ 100)
Amount removed
removed = original × (percent ÷ 100)
Reversing it
original = new ÷ (1 − percent ÷ 100)
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 250 decreased by 15% | 250 × 0.85 | 212.5, down by 37.5 |
| A 60 item at 30% off | 60 × 0.7 | 42 |
| Up 50% then down 50% | ×1.5 × ×0.5 | 75% of the original |
When you'd use it
- Working out a sale price
- Applying a discount or a pay cut
- Calculating depreciation at a fixed rate
- Finding what remains after a percentage loss
Common questions
Why does a 50% increase then a 50% decrease not return me to the start?
Because each percentage applies to a different base. Going up 50% from 100 gives 150; taking 50% off 150 removes 75, leaving 75. Percentage moves are not symmetric, which is why investment losses hurt more than equivalent gains help.
How do I find the original price before a discount?
Divide by one minus the discount. A 42 item after 30% off was 42 ÷ 0.7 = 60. Adding 30% back to 42 gives 54.6, which is wrong.
Can something decrease by more than 100%?
Not meaningfully as a quantity — a 100% decrease reaches zero. Figures beyond that only make sense where negatives are valid, such as a profit turning into a loss.