PercentBox
PercentBox

Percentage Calculator

Use this free percentage calculator to solve everyday percent problems in seconds. Choose a mode, enter your numbers, and get an instant answer with the formula shown.

Understanding percentage calculator

A percentage calculator answers the questions people ask every day: how much is a share of a total, how much did something grow, what tip or discount applies, and what number sits behind a percent. PercentBox keeps the math visible so you can learn the pattern, not only copy a result.

Good for

  • Homework or exam practice with multiple percent question types
  • Quick checks when you are not sure which specialized tool to open
  • Teaching someone the difference between “percent of” and “percent change”

Try the calculator

What is X% of Y?

Find a percentage of a number

%

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Result

Enter values to calculate

Use this free percentage calculator to solve everyday percent problems in seconds. Choose a mode, enter your numbers, and get an instant answer with the formula shown. Read related guides.

What this all-in-one tool covers

Instead of jumping between apps for school homework, shopping, and dining out, this hub lets you switch modes for “X% of Y,” reverse percentages, increase/decrease, percentage change, tips, and discounts. Each mode uses a standard formula taught in school and used in business.

If you already know which problem you have, open the dedicated pages (for example tip or discount) for longer examples. If you are exploring, stay here and change modes until the wording matches your question.

A practical workflow

Start by naming the whole and the part in plain language. For “what is 18% of my bill,” the bill is the whole and 18% is the rate. For “40 is what percent of 200,” 40 is the part and 200 is the whole. Mixing those roles is the most common source of wrong answers.

Next, decide whether you need a new value (increase/decrease/discount) or a comparison between two values (percentage change). Those look similar but use different formulas.

Checking your work

Rough mental checks catch typos: 10% should look like moving the decimal; 50% should be half; 100% should return the original number. If your result is wildly larger or smaller than those anchors, re-read which box is percent versus amount.

PercentBox shows formulas beside results so you can rebuild the same steps on paper. That habit matters for exams and for trusting a shopping or finance estimate.

Worked examples

Example calculations for Percentage Calculator
QuestionAnswer
What is 15% of 200?30
What is 20% of 50?10
What is 7.5% of 80?6

Formula reference

GoalFormula
X% of Y(X ÷ 100) × Y
X is what % of Y(X ÷ Y) × 100

FAQ — Percentage Calculator

How do you calculate a percentage?
Divide the part by the whole and multiply by 100, or multiply the whole by (percent ÷ 100). Example: 15% of 200 = 0.15 × 200 = 30.
Is this percentage calculator free?
Yes. PercentBox is free, works in your browser, and does not require an account.

Educational tool only — not tax, legal, or financial advice. Contact us with corrections.

Related percentage tools

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