Percentage Decrease Calculator
Reduce any number by a percentage and see the result as you type — exact decimal arithmetic, free, nothing to install.
Enter your values to see instant results:
Keyboard shortcuts
| Tab / Shift+Tab | Next / previous field |
| ↑ / ↓ | Step a value by 1 (Shift: 10, Alt: 0.1) |
| Enter | Copy the focused row's result |
| [ / ] | Fewer / more decimal places |
| Esc | Clear the field |
The percentage decrease formula
new = old × (1 − p ÷ 100). Taking 15% off 200: 200 × 0.85 = 170.
The multiplier view is the one worth internalizing — "decrease by 15%" simply means "keep
85%" — because it makes chained changes honest: two successive 15% cuts keep 0.85 × 0.85 =
72.25% of the original, a 27.75% total reduction, not 30%.
Going the other way — you know both numbers and want the rate of decline — is the change
formula, (new − old) ÷ old × 100, which comes out negative for a drop. A
portfolio going from $12,000 to $9,000 changed by (9,000 − 12,000) ÷ 12,000 × 100 = −25%.
Where decreases mislead
A decrease measured from a bigger base always looks smaller on the way back up. Lose 25% and you need +33.33% to recover; lose 50% and you need +100%. This asymmetry is a constant source of confusion in finance headlines ("the index regained yesterday's 5% loss" — it needs 5.26%). When precision matters, compute with the multipliers rather than adding and subtracting percents.
Shopping discounts are the friendly face of percentage decreases — the percent off calculator speaks in price, discount and savings directly, and handles the stacked-coupon case correctly.
Percentage decrease FAQ
How do I decrease a number by a percentage?
Multiply by (1 − percent ÷ 100). To take 15% off 200, multiply 200 × 0.85 = 170. One multiplication, done — no need to compute the 15% separately and subtract it.
How do I find the percentage decrease between two numbers?
Same formula as any change: (new − old) ÷ old × 100. From 80 down to 60 that's (60 − 80) ÷ 80 × 100 = −25%, a 25% decrease. Use the Change from… to… row above, or the dedicated percentage change calculator.
Can something decrease by more than 100%?
Only if it can go negative. A quantity that can't drop below zero — a price, a weight, a population — decreases at most 100%, which wipes it out entirely. Values that can cross zero, like profit or temperature, can fall by more than 100%: profit of $50 falling by 140% lands at −$20.
Why doesn't a 50% decrease undo a 50% increase?
Because the two percentages act on different bases. 200 increased 50% is 300; decreasing 300 by 50% takes half of 300, landing at 150 — not back at 200. Undoing a +50% move needs a −33.33% move. The general rule: to reverse × (1 + p), you need ÷ (1 + p).