Percentage Decrease Calculator

When a value falls — a sale price, a temperature, a score — the percentage decrease expresses the drop relative to the starting value. Enter both values to get the decrease in units and in percent.

Results

Formula

Percentage decrease measures the drop against the starting value:
% Decrease = (Old − New) ÷ |Old| × 100
A negative result means the value actually increased.

How to use this calculator

  1. Enter the original (starting) value.
  2. Enter the new, lower value.
  3. Press Calculate to see the decrease and its percentage.
Percentage Decrease Calculator — how the calculation works, illustrated
Percentage Decrease Calculator — how the calculation works, illustrated

Worked example

A phone drops in price from $120 to $90.

  1. Decrease: 120 − 90 = 30.
  2. Divide by the original: 30 ÷ 120 = 0.25.
  3. Multiply by 100: 25%.

Result: The price decreased by $30, a 25% decrease.

Frequently asked questions

Can a percentage decrease be more than 100%?

Not for values that stay positive — a 100% decrease already brings a value to zero. A decrease beyond 100% would make the value negative.

Is a 50% decrease followed by a 50% increase back to the start?

No. 100 → 50 is a 50% decrease, but 50 → 100 is a 100% increase. The base changes, so the percentages are not symmetric.

How is percentage decrease used in retail?

It expresses how much a price was marked down relative to the original price, which is also how “% off” labels are computed.

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