Relative Change Calculator
Compute the relative change between two values — the dimensionless ratio (and equivalent percent change) that tells you how much a quantity shifted relative to its starting point.
Increase relative to reference
- 1
Absolute change
V₂ − V₁ = 100 − 80 = 20 - 2
Relative change
20 ÷ |80| = 0.2500Divide by the absolute value of the reference so the sign always tracks the direction of change. - 3
Percent change
0.25 × 100 = 25 %
How does this calculator work?
Relative change is (V₂ − V₁) divided by the absolute value of the reference V₁, giving a dimensionless ratio. Multiply by 100 for percent change. A positive result means V₂ is larger; negative means smaller. The result is undefined when V₁ equals zero because division by zero has no meaningful value.
Formula
How this is calculated
Relative change measures how large a change is compared to the original value. Given a reference (starting) value V₁ and a new value V₂, relative change = (V₂ − V₁) / |V₁|. Dividing by the absolute value of V₁ ensures the sign of the result always tracks the direction of change — positive means V₂ is larger, negative means smaller — even when V₁ is negative.
The result is a pure dimensionless number: 0.25 means V₂ is 25 % larger than V₁, −0.10 means 10 % smaller. Multiplying by 100 converts it to the more familiar percent change. Relative change and percent change carry the same information; the difference is only the scale (1 vs 100).
Relative change is undefined when the reference value V₁ is exactly zero, because dividing by zero has no finite result. In that case enter a reference value that is even slightly different from zero, or use the absolute change V₂ − V₁ instead.
Frequently asked questions
They are the same quantity on different scales. Relative change = (V₂ − V₁)/|V₁| is a dimensionless ratio (e.g. 0.25). Percent change multiplies that ratio by 100 to give a percentage (25 %). The calculator reports both.
The formula divides by the reference value. Division by zero is mathematically undefined — any V₂ would imply an infinitely large relative change — so the calculator shows no result when V₁ is zero.
Relative change compares a new value to a fixed reference (order matters). Relative difference is symmetric — it compares the absolute difference to the average of the two values — so it is used when neither value is a clear "before" or reference.
Also known as
TG we-Calculate Editorial Team. (2026). Relative Change Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/relative-change-calculator
TG we-Calculate Editorial Team. "Relative Change Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/relative-change-calculator.
TG we-Calculate Editorial Team, "Relative Change Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/relative-change-calculator
@misc{wecalculate_relative_change_calculator, title = {Relative Change Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/relative-change-calculator}}, year = {2026}, note = {TG we-Calculate} }
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