Absolute Change and Relative Change Calculator

This calculator compares an old value and a new value. Enter both; you get the absolute change, in the same units as the values, and the relative change as a percentage of the old value.

Formula

Absolute change = new − old. Relative change = (new − old) ÷ |old| × 100%.

• A positive result is an increase, a negative one a decrease.
• The old value is the reference; it cannot be 0 for a relative change.

Worked Example

A value goes from 80 to 100.

1. Absolute change = 100 − 80 = 20.00
2. Relative change = 20 ÷ 80 × 100 = 25.00%

How to read the result

Absolute change answers “by how much”, in units; relative change answers “by what share”. Going back from 100 to 80 is the same 20 units but only a 20% fall, because the reference is now 100. For changes between two percentages (5% to 6%), the absolute change is 1 percentage point and the relative change is 20%.

Limits and common mistakes

• Swapping old and new changes the relative result.
• Relative change from 0 is undefined; the calculator shows Cannot compute.
• Do not average relative changes over several periods; compound them instead.

Frequently Asked Questions

What is the difference between absolute and relative change?

Absolute is new minus old in units; relative divides that by the old value.

Is percent change the same as relative change?

Yes, relative change written as a percentage.

What about a negative old value?

The calculator divides by its absolute value so that the sign shows the direction of the change.

What is a percentage point?

The absolute change between two percentages.

in o | Old (reference) value | - | 80 | -
in n | New value | - | 100 | -
out ab | Absolute change | - | n - o | 2
out rel | Relative change | % | (n - o) / abs(o) * 100 | 2