Percentage Decrease Calculator

The percentage decrease formula

Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100

Subtract the new value from the original value to find how much was lost. Divide that amount by the original value to see it as a fraction of the starting point, then multiply by 100 to get a percentage.

Worked examples

• A price drops from $50 to $40: (50 − 40) ÷ 50 × 100 = 20%
• A monthly bill falls from $120 to $90: (120 − 90) ÷ 120 × 100 = 25%
• Weight goes from 80 kg to 76 kg: (80 − 76) ÷ 80 × 100 = 5%
• A battery drops from 64.5% to 51.6% charge: (64.5 − 51.6) ÷ 64.5 × 100 = 20%

When to use a percentage decrease calculation

Use it to describe how much something shrank compared with where it started — for example a sale price, a lower bill, a drop in sales or traffic, or a reduction in a measurement. It lets you compare decreases fairly even when the starting amounts are very different.

Decreases and increases aren't symmetrical: a fall from 50 to 40 is 20%, but rising from 40 back to 50 is 25%. The original value can't be zero. If the new value is larger, use the percentage increase calculator instead.