Percentage Change Calculator
Calculates the percentage increase or decrease.
Result
- Change
- 25.00%
- Difference
- 20
How to use the percentage change calculator
- Enter the old value.
- Enter the new value.
- The results update as you type, or press Calculate.
- Read the change first, then the supporting figures below it.
Formula
% change = (new − old) ÷ |old| × 100.
Worked example
For example, with these inputs:
- Old value: 80
- New value: 100
the calculator returns:
- Change: 25.00%
- Difference: 20
Background
These calculations appear throughout the Singapore syllabus, from primary school percentages and fractions to secondary school algebra and geometry. Understanding the formula makes problem sums easier because you can recognise which quantity is missing.
Each formula has assumptions built in. Area formulas assume flat shapes, volume formulas assume regular solids and statistical measures assume the data you enter is the data you want to describe. Knowing the assumptions helps you pick the right tool.
Frequently asked questions
How does the percentage change calculator work?
It applies this formula: % change = (new − old) ÷ |old| × 100.
Can I use any units?
Yes, as long as every input uses the same unit. The answer will be in that unit (squared for areas, cubed for volumes).