A percentage decrease measures a drop against the value you started with. Sales and coupons, falling prices, shrinking budgets, weight loss and asset depreciation are all decreases. This calculator finds the rate of a drop, applies a drop to a number, or works backward from a reduced value to the original — and it always tells you how big a gain it would take to undo the decline.
How to use the percentage decrease calculator
- Choose a question from the menu.
- Percent decrease mode: enter the original value and the lower value it fell to.
- After a decrease mode: enter the original value and the percentage taken off. For repeated drops, such as an asset losing 15% of its value each year, set how many times to apply it.
- Before a decrease mode: enter the reduced value and the percentage that was removed.
- Read the result on the tape and follow the steps underneath.
Percentage decrease formulas
To apply a decrease, multiply by what remains:
To undo a decrease, divide by what remained:
Worked example: a markdown
A jacket’s price tag drops from $80 to $68.
Drop: 80 − 68 = $12
Rate: 12 ÷ 80 = 0.15, so the jacket is 15% off
Same thing as a multiplier: 80 × 0.85 = 68
Working backward from the tag: 68 ÷ 0.85 = $80
To return to $80 the price would need to rise 12 ÷ 68 ≈ 17.65%
Why 100% is the floor
For anything that can’t go negative — a price, a weight, a population — the largest possible decrease is 100%, which leaves nothing. A “150% decrease” is a misuse of the term; usually the writer meant the value fell to a third of its former size (a 66.7% decrease) or that something else grew by 150%. If the calculator reports more than 100%, your new value is below zero.
Losses are harder to recover than they look
Because a recovery is measured from the lower value, every decrease needs a larger percentage increase to get back to where it started:
| Drop | Gain needed to recover |
|---|---|
| 10% | 11.11% |
| 15% | 17.65% |
| 20% | 25% |
| 25% | 33.33% |
| 50% | 100% |
| 75% | 300% |
| 90% | 900% |
This is why a portfolio that falls 50% must double just to break even, and why retailers can advertise “up to 50% off” while still protecting margins on items they marked up first.
Stacked discounts
Store coupons are usually applied one after the other, not added together. Twenty percent off and then an extra 10% off leaves 0.80 × 0.90 = 0.72 of the price — a 28% total discount, not 30%. Set the “how many times” box to see repeated equal drops, such as three annual 15% depreciations: 0.85³ ≈ 0.614, so about 38.6% of the value is gone after three years.
Related calculators
- Shopping with a coupon or sale sticker? The discount calculator and sale price calculator show savings in dollars.
- For equipment and vehicles losing value over time, the depreciation calculator covers accounting methods.
- If you’re not sure whether a value went up or down, the percentage change calculator gives a signed answer, and the percentage increase calculator handles growth.
Frequently asked questions
How do I calculate a percentage decrease?
Subtract the new value from the original, divide by the original, and multiply by 100. A price cut from $80 to $68 is (80 − 68) ÷ 80 × 100 = 15%.
How do I take a percentage off a number?
Multiply by 1 minus the percentage as a decimal. To take 15% off $80, multiply by 0.85 to get $68. The amount saved is the difference, $12.
How do I find the original price before a discount?
Divide the sale price by the share that is left. After 15% off, 85% remains, so a $68 sale price came from 68 ÷ 0.85 = $80. Adding 15% to $68 gives $78.20, which is wrong because the discount was taken from the larger price.
Why does a 50% drop need a 100% gain to recover?
The gain is measured from the lower value. If $200 falls 50% to $100, getting back to $200 means adding $100, which is 100% of $100. The general rule is that a p% drop needs p ÷ (100 − p) × 100 percent to recover.
Is 20% off followed by 10% off the same as 30% off?
No. The second discount applies to the already reduced price, so the total multiplier is 0.80 × 0.90 = 0.72. That is a 28% total discount, slightly less than 30%.