Percentage Calculator
Three modes: percent of a whole, part as a percent of a whole, and recovering the whole when a part and percent are known.
Limitation: Educational arithmetic only.
How to Use the Percentage Calculator
Pick the question you are asking, enter the two known numbers in order, and read the result with the interpretation line.
Choose the mode that matches your question.
Order matters
“20 is what percent of 80?” is not the same as “80 is what percent of 20?” Keep part and whole identified.
What Each Mode Returns
The primary output is the missing number for the selected mode. Details repeat the formula and a one-line interpretation so you can copy the wording into homework or reports.
Worked Percentage Examples
What is 25% of 80?
Inputs
Result
80 × 0.25 = 20.
20 is what percent of 80?
Inputs
Result
20 ÷ 80 × 100 = 25.
20 is 25% of what?
Inputs
Result
20 ÷ 0.25 = 80.
Percent vs percentage points
A rise from 10% to 12% is a 2 percentage-point rise, but a 20% relative increase. See the companion guide.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorPercentage Formulas
All three modes rearrange the same relationship: part = whole × (percent ÷ 100).
Formula
Percent of
result = whole × (percent ÷ 100)
Is what percent
percent = (part ÷ whole) × 100
Percent of what
whole = part ÷ (percent ÷ 100)
Scientific Background
These are rearrangements of the definition of percent as “per hundred.” They do not measure change over time—use the percentage-change or percentage-increase tools for that.
Sources & review
Percentage Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.
Last reviewed
July 22, 2026
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