What this calculator does
Percentages appear everywhere: discounts, raises, interest, tips and comparisons. The key is knowing which value is the base and whether the change is relative or absolute.
This calculator handles four common cases: percent of a value, increase, decrease and percentage difference. It avoids the classic mistake of adding percentages that apply to different bases.
Percentage formulas
Value = Base × Rate ÷ 100 For an increase, multiply by (1 + rate/100). For a decrease, multiply by (1 − rate/100). Percentage difference divides the change by the starting value.
How this calculator works
- 01
Choose the calculation
Select percent of, increase, decrease or difference.
- 02
Enter the base and rate
The result updates instantly as you type.
- 03
Check the base
Make sure the percentage refers to the value you intend, especially with stacked discounts.
Frequently asked questions
Why are 20% + 20% not 40%?
The second increase applies to the already increased value. 100 plus 20% is 120; another 20% adds 24, for 144 total.
What is the difference between percent and percentage points?
Percent describes a relative change, while percentage points describe an absolute difference between two percentages. Going from 10% to 12% is +2 percentage points but +20% relative.
How do I calculate a discount?
Multiply the original price by the discount rate and subtract it, or multiply directly by (1 − rate/100).
Data basis: 2026 · Annual constants live in structured JSON files and are updated once a year.
Results are unverified model calculations and do not replace tax, legal or financial advice.