Percentage Calculator
Find what percent one value is of another, a percentage of a value, or a percent change.
Inputs
- Calculate
- A
- B
What it does
Three common percentage questions: what % A is of B, what A % of B is, and the percent change from A to B.
Where it's used
Discounts, marks, growth rates, tolerances and efficiency.
How to use it
- Choose the question.
- Enter A and B.
- Read the answer.
The formula explained
- A is ?% of B
- (A / B) × 100
- A% of B
- A / 100 × B
- Change A → B
- (B − A) / A × 100
Worked example
A price rising from 80 to 100.
Inputs:
- Calculate: Percent change from A to B
- A: 80
- B: 100
The calculator gives:
- Result: 25 %
Tips and common mistakes
- Percent change is measured from the starting value (A).
- A 50 % fall followed by a 50 % rise does not return to the start.
- “Percentage points” describe a difference between two percentages.
Questions people ask
Why isn’t a fall the same size as the rise?
Percent change is measured from the starting value. 80 → 100 is +25 %, but 100 → 80 is −20 %, because the second change starts from a bigger number.
How do I remove a percentage that was added?
Divide by (1 + rate), don’t subtract. A price of 1 180 including 18 % tax was 1 180 / 1.18 = 1 000 before tax — subtracting 18 % would give 967.6.
What are percentage points?
The plain difference between two percentages. An interest rate going from 10 % to 12 % rises by 2 percentage points, which is a 20 % increase.
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Enter your values to get the result with the formula, substituted values and an explanation of each step.