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Relative Change Calculator

Determine the relative change in your variables with our relative change calculator.

Clear
Relative change+30%
As a decimal0.3
Absolute change15
Ratio1.3

The formula

relative change = (new − reference) ÷ |reference|

What a percentage is

"Per cent" means "per hundred", so a percentage is just a fraction with 100 on the bottom. 15% is 15/100, which is 0.15 as a decimal. Every percentage calculation is therefore multiplication or division by a decimal — the percent sign is bookkeeping, not a new operation.

The three questions

Almost every percentage problem is one of three:

  • What is P% of N? Multiply: N × P/100
  • A is what percent of B? Divide: A/B × 100
  • A is P% of what? Divide the other way: A ÷ (P/100)

Recognising which one you have is most of the work; the arithmetic is straightforward once you do.