How to use Percentage Calculator
- Pick a calculationIn Calculation, choose What is A% of B?, A is what percent of B?, Percentage change from A to B or Add A% to B.
- Enter both valuesType numbers into Value A and Value B. Decimals and negative numbers are accepted.
- Run the calculationPress Run Percentage Calculator and the answer appears in the result panel, ready to copy.
Common uses
- Working out a tip or a tax amount
- Checking how much a price or salary has changed
- Finding what share of a target you have reached
Frequently asked questions
How do I use Percentage Calculator?
1. Pick a calculation: In Calculation, choose What is A% of B?, A is what percent of B?, Percentage change from A to B or Add A% to B. 2. Enter both values: Type numbers into Value A and Value B. Decimals and negative numbers are accepted. 3. Run the calculation: Press Run Percentage Calculator and the answer appears in the result panel, ready to copy.
Which formulas does it use?
A% of B is B × A ÷ 100. A as a percent of B is A ÷ B × 100. Percentage change is (B − A) ÷ |A| × 100, and Add A% to B is B + B × A ÷ 100.
Why does the result say Undefined?
Dividing by zero has no answer. A is what percent of B is undefined when B is 0, and percentage change is undefined when the starting value A is 0.
Can I subtract a percentage?
Yes. In Add A% to B, enter a negative A such as −20 to take 20% off B. Results are rounded to four decimal places, or two for percentage change; for stacked discounts and sales tax, the Discount Calculator is handier.
Where is the calculation done?
Your two values and the chosen mode are sent to the GigaTools server, calculated and returned straight away. The response is marked private and not cached, and the tool does not save your numbers.