Percentage Change Calculator
Try it
- Percentage Change
- Absolute Change
Formula
percentage_change = ((new_value − old_value) ÷ |old_value|) × 100Worked Example
Inputs
- Original Value
- 100.00
- New Value
- 120.00
Result
- Percentage Change
- 20.00%
- Absolute Change
- 20.00
100.00 changed to 120.00: a 20.00% change (absolute change: 20.00).
Frequently Asked Questions
- What is the formula for percentage change?
- Percentage Change = ((New Value − Old Value) ÷ |Old Value|) × 100. A positive result means an increase; a negative result means a decrease.
- How do I calculate a percentage increase?
- Subtract the original value from the new value, divide by the original, then multiply by 100. Example: from 200 to 250 → (250 − 200) ÷ 200 × 100 = 25% increase.
- How do I calculate a percentage decrease?
- The same formula applies. If the new value is less than the old, the result will be negative. Example: from 200 to 160 → (160 − 200) ÷ 200 × 100 = −20% (a 20% decrease).
- Why does the formula use the absolute value of the original?
- Using |old_value| ensures the sign of the percentage change correctly reflects the direction of change regardless of whether the original value is positive or negative.
- What is the difference between percentage change and percentage points?
- Percentage change measures a relative change (e.g. a rate rising from 10% to 12% is a 20% change). Percentage points measure the absolute arithmetic difference (10% to 12% = 2 percentage points). They are different concepts.
Source & Methodology
- Tier 1 — Government / Official
- Office for National Statistics: Measures of Change
UK Government ONS methodology defining percentage change as ((new - old) / |old|) × 100. Authoritative definition used in UK national statistics; global mathematical standard. - Tier 1 — Government / Official
- National curriculum in England: mathematics programmes of study
UK DfE KS4 curriculum includes percentage change as a required mathematical concept.