Percentage Decrease Calculator
Calculate the percentage decrease from one value to another. Works for price drops, discounts, salary cuts, loss calculations, and any percent reduction. Runs privately in your browser.
How to Calculate Percentage Decrease
Percentage decrease measures how much a value has fallen relative to its original amount. The formula subtracts the new value from the original, divides by the original, and multiplies by 100. A positive result confirms a decrease; if the new value is actually higher, the result indicates an increase instead.
Percentage Decrease Formula
Percentage Decrease = ((Original Value − New Value) / Original Value) × 100
New Value = Original Value × (1 − Percentage Decrease / 100)
Where:
- Original Value = The starting number (before the decrease)
- New Value = The ending number (after the decrease)
Example Calculations
Example 1: Price Drop
Original price: $80 → Sale price: $64
- Decrease = ($80 − $64) / $80 × 100 = 20% decrease
Example 2: Stock Market Loss
Bought at: $150 → Current: $127.50
- Decrease = ($150 − $127.50) / $150 × 100 = 15% decrease
Example 3: Weight Loss
Starting weight: 200 lbs → Current weight: 185 lbs
- Decrease = (200 − 185) / 200 × 100 = 7.5% decrease
Percentage Decrease vs Discount
A discount and a percentage decrease are mathematically the same thing. A "20% off" sale means the price decreased by 20% from the original. This calculator works for both — enter the original price and sale price to find the discount percentage, or enter the original price and discount percentage to find the sale price.
Why Percentage Decrease Is Not the Inverse of Percentage Increase
A common mistake: if something increases by 25% and then decreases by 25%, you do NOT end up where you started. Starting at 100, a 25% increase gives 125. Then a 25% decrease of 125 gives 93.75 — not 100. This asymmetry is important in finance, investment, and pricing calculations.