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Percentage increase calculator

Find the percentage change between two values, or calculate the result of increasing or decreasing a number by a given percentage.

  • Free
  • No sign-up
  • In your browser

Result

Enter both values to see the result.

How to use this tool

  1. Choose the type of calculation: change between two values, increase a value by a %, or decrease it by a %.
  2. Enter the two numbers. Use a dot for decimals (12.5).
  3. The result appears instantly, with a sentence that explains it and the absolute difference between both values.
  4. Press “Copy” if you need to paste the result somewhere else.

How percentage change is calculated

Percentage change compares the difference between the new value and the old value with the old value: (new − old) / old × 100. A positive result is an increase; a negative one is a decrease.

For example, if a product goes from 50 to 65, the difference is 15, and 15 / 50 × 100 = 30%. If it goes from 80 to 60, the difference is −20, and −20 / 80 × 100 = −25%, a 25% decrease.

When the starting value is 0, percentage change is undefined, because you can't divide by zero. If the starting value is negative, the calculator divides by its absolute value so the sign of the result correctly shows whether the value went up or down (from −10 to −5 is a 50% increase).

Increasing or decreasing a number by a percentage

To increase a value by a percentage, multiply it by (1 + percentage / 100). To decrease it, multiply by (1 − percentage / 100). So raising 1,200 by 15% gives 1,200 × 1.15 = 1,380, and lowering 250 by 12% gives 250 × 0.88 = 220.

Going up and down by the same percentage doesn't get you back

This is a very common mistake. If 100 goes up 20%, it becomes 120, but if 120 then goes down 20%, it ends at 96, not 100. The second percentage applies to a larger base, so it takes away more than the first one added.

To undo a 20% increase you need a decrease of about 16.67% (20 / 120 × 100), since 120 × (1 − 0.1667) ≈ 100.

Percent change vs. percentage points

When the thing that changes is itself a percentage (an interest rate, a tax rate, a market share), it helps to tell two measures apart. If a rate goes from 2% to 3%, it has risen by 1 percentage point, but in relative terms it has increased by 50%, because 1 is half of 2.

Neither is wrong, but they say different things. This calculator gives the relative change; percentage points are simply the difference between the two percentages.

Examples

A raise from $4,500 to $4,770 a month

Choose “Change between two values” and enter 4500 and 4770. Result: +6%, an increase of $270.

A price drops from 80 to 60

With “Change between two values”, enter 80 and 60. Result: −25%, a decrease of 20.

Raising a $1,200 rent by 15%

Choose “Increase by %” and enter 1200 and 15. The new amount is $1,380, $180 more.

Cutting a 250 budget by 12%

Choose “Decrease by %” and enter 250 and 12. Result: 220, that is, 30 less.

Frequently asked questions

What is the formula for percentage increase?

Subtract the old value from the new value, divide the result by the old value and multiply by 100: (new − old) / old × 100. If the result is negative, it's a decrease.

Can a percentage increase be more than 100%?

Yes. A 100% increase means the value has doubled, and a 150% increase means it's now 2.5 times the original (for example, from 20 to 50). A decrease, on the other hand, can't exceed 100% if the values are positive, because that would mean going below zero.

Why can't I calculate the change if the starting value is 0?

Because the formula divides by the starting value, and division by zero is undefined. In that case it makes more sense to talk about the absolute difference (for example, “it went from 0 to 10”) than about a percentage.

Is going up 10% twice the same as going up 20%?

No. Two consecutive 10% increases are the same as multiplying by 1.1 × 1.1 = 1.21, a total increase of 21%. Each percentage applies to the result of the previous one.

Is my data sent to a server?

No. All calculations happen in your browser and the numbers you type aren't sent to any server.

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