What is a Percentage Change Calculator?
Percentage change trips people up because the base matters: going 100→150 is +50%, but 150→100 is −33%, not −50%.
Enter the old and new values; the tool applies change ÷ old × 100 and labels the direction for you.
How to use the Percentage Change Calculator
- Enter the old (from) value.
- Enter the new (to) value.
- Read the signed percentage and absolute change.
Frequently asked questions
What is the formula?
(new − old) ÷ |old| × 100. The old value is always the base.
Why is 100→150 +50% but 150→100 −33%?
Because the base changes: +50 on a base of 100, −50 on a base of 150.
What if the old value is 0?
Percentage change from zero is mathematically undefined — the tool asks for a non-zero base.
Percentage change vs percentage points?
10%→15% is a +50% relative change but +5 percentage points. Say “points” when comparing two percentages.