How it’s calculated
- Difference
- equals New Value − Original Value
- Percentage Change
- equals (Difference ÷ |Original Value|) × 100
The change is always measured against the original value. Using its absolute value keeps the direction correct when the original is negative — a loss narrowing from −$10,000 to −$4,000 shows as a 60% improvement.
Worked example
Monthly revenue rose from $42,000 in March to $50,400 in April, then fell back to $42,000 in May.
- March → April: ($50,400 − $42,000) ÷ $42,000 = +20%
- April → May: ($42,000 − $50,400) ÷ $50,400 = -16.67%
The same $8,400 swing is a 20% increase but only a 16.67% decrease, because each is measured from a different starting point. A 20% gain doesn’t undo a 20% loss.
Assumptions and limitations
- When the original value is zero, percentage change is undefined. The calculator shows the absolute difference instead.
- Percentage change is different from percentage-point change. A margin moving from 20% to 25% is a 5-point increase but a 25% change.
- Results are shown to two decimal places.
Results are estimates for information only and are not financial, tax or legal advice. See our disclaimer.