Koc.so / Tools Method

A precise two-number utility

Percentage change,
made unmistakable.

Enter where a value started and where it ended. Get the percentage increase or decrease, the raw change, and the exact calculation.

Enter the values

Use a decimal point. Grouping commas are optional.

Starting point

Ending point

Try

Percentage change

—

Waiting for both values

Enter an original value and a new value to begin.

Absolute change
—
New ÷ original
—

(new − original) ÷ |original| × 100

The method

Change measured against where you started.

Percentage change

new − original|original| × 100

The original value is the reference point. Its absolute magnitude is used in the denominator so the sign still clearly indicates the direction of change when the starting value is negative.

A

Read the direction

A positive result means the value increased. A negative result means it decreased. Zero means there was no change.

B

Zero has no baseline

A percentage change from zero is undefined because the formula would divide by zero. The raw change can exist, but no finite percentage can describe it.

Worked example

From 80 to 100

  1. Find the change100 − 80 = 20
  2. Compare with the start20 ÷ 80 = 0.25
  3. Convert to percent0.25 × 100 = 25%

The value increased by 25%.

Useful distinctions

Change is directional.

Percentage change is for an ordered journey from an original value to a new value. If neither value is the starting point, percentage difference may be the better measure.

Why are a 20% increase and a 20% decrease not opposites?

They use different starting values. Increasing 100 by 20% gives 120. Decreasing 120 by 20% gives 96, because the second percentage is based on 120.

Can I use negative values?

Yes. This calculator divides by the absolute magnitude of the original value, keeping the result’s sign aligned with whether the new value moved up or down.

How many decimal places are shown?

Results use up to six decimal places for percentages and up to twelve significant digits for other values. Calculations use the browser’s full numeric precision before display rounding.

Is my data stored or sent anywhere?

No. Calculations happen locally in your browser. There are no accounts, cookies, analytics, or network requests. A valid calculation may appear in the page URL so you can copy and share it.