About this calculator
The Percentage Decrease Calculator finds how much, in percentage terms, a value has dropped between an initial amount and a final amount.
How is percentage decrease calculated?
Percentage decrease is calculated by subtracting the new value from the original value, dividing that difference by the original value, and multiplying by 100: Percentage Decrease = (Original − New) ÷ Original × 100. The result is always expressed relative to the original (starting) value, not the new one.
Percentage decrease vs. a simple difference
A plain difference (subtracting one number from another) tells you the raw amount something changed by, but not how significant that change is. A price dropping by $10 is a huge deal if it started at $20, but barely noticeable if it started at $1,000. Percentage decrease puts the change in proportion to the starting value, which is what usually matters for comparisons.
Where percentage decrease is used
This calculation is common for tracking falling prices, declining sales or revenue, weight loss, population decline, or any metric that's shrinking over time. It's also frequently confused with percentage points, which is a different (and non-interchangeable) way of comparing two percentages directly.