How to use the percentage calculator
- Pick the calculation type.
- Enter A and B.
- Read the answer instantly — plus the difference and ratio.
The formula
A% of B = A/100 × B; A as % of B = A/B × 100; % change = (B − A)/|A| × 100
Percent change uses the starting value (A) as the base.
Worked example
Going from 80 to 98 is a 22.5% increase. Going back from 98 to 80 is an 18.4% decrease — the base changed.
Tips from the numbers
- Percentage points ≠ percent: a rate rising from 4% to 5% is 1 point, but a 25% increase.
- For multi-year growth, use CAGR in the ROI calculator.
Watch: learn the concept
Frequently asked questions
How do I calculate a discount?
Use 'A% of B' with A as the discount and B as the price, then subtract the result.
Why are increases and decreases not symmetrical?
Each uses a different starting value as the base.
Can I use negative numbers?
Yes; percent change uses the absolute value of the starting number as the base.
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