How do I calculate X percent of a number?

Select X% of Y mode, enter the percentage in the first field and the number in the second. The result is (percentage ÷ 100) × number.

How do I find what percent one number is of another?

Use X is what % of Y mode. Enter the part in the first field and the whole in the second. Result = (part ÷ whole) × 100.

How is percentage change calculated?

Percent change = ((new value − original value) ÷ original value) × 100. A positive result is an increase; negative is a decrease.

Can I calculate increase or decrease by a percentage?

Yes. Increase by % adds that percentage of the base number. Decrease by % subtracts it. Example: 200 increased by 10% = 220.

Is this calculator free and private?

Yes. All calculations run in your browser — no signup, no upload, no data stored.

Students

Percentage Calculator

Free percentage calculator for students — find X% of Y, percent change, increase/decrease, and what percent one number is of another.

100% client-side — your data never leaves this tab

Percentage (X)Number (Y)

Result

100

20% × 500 = 100

20% of 500 is 100.

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What is Percentage Calculator?

Percentage Calculator helps students solve everyday percent problems fast — find what is X% of Y, calculate what percent one number is of another, measure percent change between two values, and apply increase or decrease by a percentage. Clear formulas and step-by-step explanations make it ideal for math homework, exam prep, marks calculation, discounts, and grade improvement tracking. Free, instant, and private.

Percentage calculations run entirely in-browser; your numbers are never uploaded.

How to use Percentage Calculator

1Choose a calculation mode: X% of Y, X is what % of Y, % change, increase by %, or decrease by %.
2Enter the two numbers in the input fields — labels change based on the selected mode.
3Read the result, formula, and plain-language explanation on the right.
4Switch modes to solve different problem types without leaving the page.

Examples

What is 20% of 500?

Formula: 20% × 500 = 100

Mode: X% of Y → 20 and 500 → Result: 100

Marks percentage

Scored 42 out of 50 = 84%.

Mode: X is what % of Y → 42 and 50 → Result: 84%

Percent change

Mode: % change → Original 80, New 100 → Result: 25% increase

Tips & common mistakes

Use X is what % of Y for exam scores: marks obtained vs total marks.
Percent change mode shows increase or decrease from an original value — useful for grade trends.
Increase/decrease modes apply a percentage to a base number (e.g. 15% raise on salary).
Double-check word problems: identify which number is the part vs the whole before choosing a mode.

Who uses this tool?

Students calculating exam percentages and semester grade improvements.
Commerce students solving discount, markup, and profit percentage problems.
Anyone checking what percent one value is of another for reports or presentations.
Teachers demonstrating percentage formulas with live numeric examples.

Frequently asked questions

How do I calculate X percent of a number?: Select X% of Y mode, enter the percentage in the first field and the number in the second. The result is (percentage ÷ 100) × number.
How do I find what percent one number is of another?: Use X is what % of Y mode. Enter the part in the first field and the whole in the second. Result = (part ÷ whole) × 100.
How is percentage change calculated?: Percent change = ((new value − original value) ÷ original value) × 100. A positive result is an increase; negative is a decrease.
Can I calculate increase or decrease by a percentage?: Yes. Increase by % adds that percentage of the base number. Decrease by % subtracts it. Example: 200 increased by 10% = 220.
Is this calculator free and private?: Yes. All calculations run in your browser — no signup, no upload, no data stored.