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Percentage Decrease Calculator

Find how much a value dropped in percent, or reduce any number by a percentage. The percentage decrease calculator shows the difference and every step, so you can check the working by hand.

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Calculation

Percentage decrease
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How to use the Percentage Decrease Calculator

  1. Choose a tab: Decrease from A to B to measure a drop, or Decrease a value by P% to reduce a number.
  2. Enter the original value and the new value, or the value and the percentage.
  3. Press Calculate. You get the percentage decrease and the difference, or the reduced value and the amount taken off.

How it works

Decrease from A to B:

decrease % = (A − B) ÷ |A| × 100

Decrease a value by P%:

new value = V × (1 − P ÷ 100)
  • A: the original value
  • B: the new value
  • V: the value to reduce
  • P: the percentage to take off

For a negative original value, this calculator divides by its absolute value. From −80 to −100, the decrease is (−80 − (−100)) ÷ 80 × 100 = 25%. This convention describes the direction and size of the numeric change; a change in a negative balance may need more context. With a positive starting value, it is the usual percentage decrease formula.

For the denominator, recovery percentage, or successive reductions, read how to calculate percentage decrease from the original value.

Examples

  • From 80 to 60 is a 25% decrease (−20).
  • 250 decreased by 40% is 150 (−100).
  • A city that shrank from 316,000 to 309,680 people fell by 6,320, which is a 2% decrease.
  • A price cut from $49.99 to $39.99 is a 20% decrease (−$10.00, rounded to two decimals).

Why a decrease and an equal increase don't cancel out

Take 80 and cut it by 25%: you get 60. Now raise 60 by 25%: you get 75, not 80. The increase is worked out on the smaller number, so 25% of 60 is only 15.

To get back to where you started after a 25% drop, you need a 33.3% rise. This catches people out with prices, salaries, and investment returns, where a loss needs a bigger gain to recover.

How to calculate a percentage decrease by hand

You need two numbers: the value before the drop and the value after it. The calculation takes three steps.

  1. Subtract the new value from the original value to get the drop. 316,000 − 309,680 = 6,320.
  2. Divide the drop by the original value. 6,320 ÷ 316,000 = 0.02.
  3. Multiply by 100 to turn it into a percentage. 0.02 × 100 = 2%.

The most common mistake is dividing by the new value. 6,320 ÷ 309,680 is 2.04%, which answers a different question: how much the value would have to rise to get back. Percent reduction, percent loss, and percent off all use the same formula, with the starting value underneath.

To go the other way and take a percentage off a number, multiply by what is left. 20% off $80 leaves 80%, and $80 × 0.8 = $64. The Decrease a value by P% tab does this for you.

Limitations

  • An original value of 0 gives an undefined-result message.
  • If the new value is higher than the original, the result is negative. Use the percentage increase calculator for growth.
  • Reducing a value by more than 100% gives a negative result, with a note.

Read the guide

Calculate a percentage decrease

Measure a drop from the original value, see why a 25% fall needs a 33.3% rise to recover, and how two discounts combine.

Frequently asked questions

How do I calculate a percentage decrease?

Subtract the new value from the original value, divide by the absolute value of the original, and multiply by 100. For a positive original value, that is the usual (original − new) ÷ original × 100 formula. A starting value of zero is undefined.

What is the percentage decrease from 316,000 to 309,680?

2%. The drop is 6,320, and 6,320 divided by 316,000 is 0.02, or 2%.

Is percent reduction the same as percentage decrease?

Yes. Percent reduction, percent loss, and percentage decrease all divide the drop by the original value and multiply by 100.

Can a decrease be more than 100%?

Only if the value goes below zero, for example a profit turning into a loss. For prices and quantities, 100% is the maximum.

Often used together with Percentage Decrease Calculator.