Percent Change Calculator

Enter an old value and a new value to see the percentage increase or decrease. The percent difference between the two numbers is shown as well.

Percent change
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Difference–
Percent difference–
Multiplier–

The percent change formula

Percent change = (new − old) ÷ |old| × 100

A positive result is a percentage increase and a negative result is a percentage decrease. The calculator also shows the multiplier, the number you multiply the old value by to get the new one. A 30% increase is a multiplier of 1.3, and a 25% decrease is 0.75.

Worked examples

  • Price increase: a coffee goes from $4.00 to $4.60. (4.60 − 4.00) ÷ 4.00 × 100 = 15% increase.
  • Weight loss: from 200 lb to 185 lb is (185 − 200) ÷ 200 × 100 = −7.5%, a 7.5% decrease.
  • Website traffic: from 12,000 to 18,000 visits a month is a 50% increase.

Percent difference

When neither number is the "starting" one, for example comparing prices at two stores, use percent difference instead. It divides the gap by the average of the two numbers:

Percent difference = |a − b| ÷ ((a + b) ÷ 2) × 100

For 50 and 65 the percent difference is 15 ÷ 57.5 × 100 ≈ 26.09%, while the percent change from 50 to 65 is 30%.

Common mistakes

  • Dividing by the new value. Always divide by the original value for percent change.
  • Adding percent changes. Up 10% then down 10% is not 0%: 100 → 110 → 99, an overall 1% drop.
  • Mixing up points and percent. An interest rate moving from 5% to 6% is up 1 percentage point, or a 20% increase.

Last reviewed October 2026.

Frequently asked questions

How do I calculate percent change?

Subtract the old value from the new value, divide by the old value, and multiply by 100. From 50 to 65 is (65 − 50) ÷ 50 × 100 = 30%.

What does a negative percent change mean?

It means the value went down. A drop from 80 to 60 is a −25% change, which you can also describe as a 25% decrease.

What is the difference between percent change and percent difference?

Percent change has a direction: it compares a new value with an original one. Percent difference compares two values with no "before" and "after", dividing the gap by their average, so the answer is the same whichever number you put first.

Why does a 50% drop need a 100% gain to recover?

Because each change is measured from a different starting point. $100 falling 50% leaves $50. To get back to $100, the $50 must double, which is a 100% increase.

Can I calculate percent change from zero?

No. Percent change divides by the starting value, and dividing by zero is undefined. Describe the change in plain numbers instead, for example "up from 0 to 40".