Percent Change Calculator

How to read the result

Percent change answers “how did this number move, relative to where it started?” Enter the earlier figure first and the later figure second. The calculator divides the difference by the earlier figure.

From 120 to 90, the difference is −30. Divide −30 by 120 and you get −0.25, or −25%. The label on the result says decrease, so you do not have to interpret the sign alone. From 90 back to 120 would be a 33.3333% increase. The trip down and the trip up are not mirror images, because each one uses its own starting point.

If the original value is 0, percent change is undefined. A population, a price, or a balance that truly starts at zero has no percentage move to report. Say what the new number is instead, or compare the two readings with percentage difference when neither one is “the original.”

A payroll example

Suppose overtime hours fall from 16 to 12. The change is (12 − 16) / 16 × 100 = −25%. The hours dropped by 4, which is a quarter of the original 16. If next month they return from 12 to 16, the increase is (16 − 12) / 12 × 100 = 33.3333%. Reporting both figures as “25%” would hide that difference.

Open 120 to 90 on the main calculator if you want a link you can send to someone else.