How to use the Percentage Increase
- Enter the original (starting) value.
- Enter the new value.
- Read the percentage change — the label tells you whether it is an increase or a decrease.
- Use the multiplier when you need to apply the same change to other figures.
How the calculation works
Percentage change is always measured against the starting value: (new − old) ÷ old × 100. Which number sits in the denominator is the whole game. A price moving from 80 to 100 is a 25% increase; moving back from 100 to 80 is a 20% decrease. The absolute change is 20 in both directions, but the base differs, so the percentages do not match.
That asymmetry has a practical consequence worth remembering: a 50% fall needs a 100% rise to recover. It also means successive percentage changes do not add. Two consecutive 10% rises give 21%, not 20%, because the second applies to the already-increased base. To chain changes, multiply the multipliers — 1.10 × 1.10 = 1.21 — rather than summing the percentages.
Percent change = (new − old) / |old| × 100 ; multiplier = new / oldSource: Standard definition of relative change used in statistics and financial reporting.
Worked example
Monthly site traffic rises from 12,400 sessions to 15,810.
- Difference: 15,810 − 12,400 = 3,410.
- Divide by the original: 3,410 ÷ 12,400 = 0.275.
- Multiply by 100.
A 27.5% increase, a multiplier of 1.275.
Frequently asked questions
Why isn't a 20% drop reversed by a 20% rise?+
The rise applies to the smaller post-drop base. You need a 25% rise to undo a 20% drop.
What is the difference between percent change and percentage points?+
A rate moving from 4% to 6% is a 2 percentage-point rise but a 50% relative increase. Reports often conflate the two.
Can the original value be zero?+
No — dividing by zero leaves percentage change undefined. Report the absolute change instead.
How do I chain several changes?+
Multiply the multipliers together rather than adding the percentages.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.