Percentage Change Calculator

Measure the relative increase or decrease between an original and a new value.

Your inputs

Calculated in your browser. Your inputs stay on this device.

Starting values are examples. First click or keyboard focus clears an example so you can enter yours. Reset restores the examples.

Your result

Enter your values to calculate.

Compare scenarios

Keep up to three results and their inputs during this visit. Reset clears the comparison.

Behind the answer

(new − original) ÷ |original| × 100

How to use this calculator

The absolute original value is the reference magnitude. The sign indicates an increase or decrease. You can also solve for a missing original or new value. Reverse solving requires nonnegative values and uses new = original × (1 + change/100).

Enter find, original value, new value and review the remaining options.
Select Calculate or change a value to update the result. Read the result label and units before copying.
Use Reset to restore the worked starting values.

Formula and method

(new − original) ÷ |original| × 100

Change from zero is undefined. Negative baselines use the absolute-baseline convention.

Worked example

From 80 to 100 is a 25% increase.

Questions about percentage change calculator

Why is change from zero undefined?

The formula divides the difference by the magnitude of the original value. Division by zero is undefined. For a negative original value this tool uses its absolute magnitude; state that convention when comparing results.

Choose the tool for your question

Percentage: Find a part, a percentage share, or the whole.

What assumptions should I check?

Change from zero is undefined. Negative baselines use the absolute-baseline convention.

Are my inputs saved?

Calculations run in your browser. We store only tool IDs for favorites and recent tools. A calculation link contains your inputs only when you explicitly choose to copy one.