Prices fall, weight drops, sales dip. To describe any of those changes clearly, you need the percentage decrease. The formula is close to its mirror image, the percentage increase — with one detail worth knowing.
The percentage decrease formula
Percentage decrease = (old value − new value) ÷ old value × 100
A jacket drops from $80 to $60:
(80 − 60) ÷ 80 × 100 = 25% decrease.
Find the difference, divide by the original value, multiply by 100.
How to reduce a number by a percentage
Multiply by (1 − percentage ÷ 100).
Reducing 200 by 15%: 200 × 0.85 = 170.
Worked examples
- Weight: 90 kg → 81 kg. Decrease = 9 ÷ 90 = 10%.
- Website visits: 12,000 → 9,000. Decrease = 3,000 ÷ 12,000 = 25%.
- Electricity bill: $150 reduced by 12%. 150 × 0.88 = $132.
Increase and decrease aren't symmetrical
Because the base changes, the same percentage in opposite directions doesn't cancel out:
- 100 up 25% is 125, but 125 down 25% is 93.75.
- To undo a 20% decrease, you need a 25% increase (80 × 1.25 = 100).
A percentage decrease can never exceed 100% for a quantity that can't go below zero — a 100% decrease means it's gone entirely.
Percentage decrease vs percentage points
If an unemployment rate falls from 10% to 8%, it dropped 2 percentage points, but the rate itself fell by 20% (2 ÷ 10). Both statements are correct; they answer different questions, so always check which one you're reading.
Calculate it instantly
The Percentage Decrease Calculator reduces a number by a percentage or finds the percentage decrease between two values, and flags it if the change is really an increase.
Common mistakes
- Dividing by the new value. Always divide by the starting value.
- Assuming a decrease and an increase of the same size cancel. They don't.
- Mixing up percent and percentage points.
FAQ
How do I find the value before a decrease? Divide the new value by (1 − percentage ÷ 100). If a price is $60 after a 25% drop, the original was 60 ÷ 0.75 = $80.
Is a negative percentage change the same as a decrease? Yes — a change of −25% is a 25% decrease.
Can I use this for discounts? Absolutely. A discount is just a percentage decrease in price.
Try it now
Use the free Percentage Decrease Calculator — no sign-up.
Related reading
Read How to Calculate Percentage Increase for the other direction, or How to Calculate a Discount. Browse the full blog for more guides.