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Percentage Calculator

Three calculators in one: find a percent of a number, work out what percent one number is of another, or measure a percentage change between two values.

What is X% of Y?
Find a percent of a number.
% of
Enter values and press Calculate to see your result.
X is what % of Y?
Find a percent from a ratio.
of
Enter values and press Calculate to see your result.
Percentage change
From an old value to a new value.
→
Enter values and press Calculate to see your result.

How to Use This Percentage Calculator

Pick the calculator that matches your question, type two numbers, and press Calculate. Each result shows the exact formula used so you can verify the math by hand.

1
Percent of a Number
Answers “What is X% of Y?” — discounts, tips, tax.
2
Ratio to Percent
Answers “X is what % of Y?” — scores, conversion rates.
3
Percentage Change
Measures increase or decrease between two values.

What Is a Percentage?

A percentage rescales any ratio onto a 0–100 axis so values of any size can be compared at a glance.

The origin and meaning

The word comes from the Latin per centum, meaning “by the hundred.” So 25% literally means 25 out of every 100, or the fraction 25⁄100, or the decimal 0.25.

Why it's useful

Percentages let us compare quantities on a common scale — a score of 47 out of 80 and 62 out of 100 are easier to compare when both are converted to percentages (58.75% vs 62%).

The Percentage Formulas

All three calculators rely on these three formulas. Hover any formula for a plain-English explanation.

Percent of a Number
(Percent ÷ 100) × Value
Ratio to Percent
(Part ÷ Whole) × 100
Percentage Change
((New − Old) ÷ |Old|) × 100

Worked Examples

Three real-world walkthroughs. Expand any example to see the step-by-step math.

Sales Tax

A $48 item with 8.5% tax: (8.5 ÷ 100) × 48 =

$4.08 tax · $52.08 total

Show steps
  1. Convert 8.5% to 0.085
  2. Multiply 0.085 × 48 = 4.08
  3. Add tax to price: 48 + 4.08 = 52.08

Test Score

42 correct out of 50 questions: (42 ÷ 50) × 100 =

84%

Show steps
  1. Divide part by whole: 42 ÷ 50 = 0.84
  2. Multiply by 100: 0.84 × 100 = 84
  3. Add the % sign → 84%

Price Increase

Subscription from $9 to $12: ((12 − 9) ÷ 9) × 100 ≈

33.33% increase

Show steps
  1. Find the change: 12 − 9 = 3
  2. Divide by the original: 3 ÷ 9 ≈ 0.3333
  3. Multiply by 100 → 33.33%

Common Use Cases

Percentages show up in everyday decisions — from grocery receipts to interest rates. Here are the situations people use this calculator for most.

Shopping discounts & sale prices
Restaurant tips & service charges
Sales tax & VAT calculations
Exam grades & test scores
Statistics, polling & surveys
Finance: interest, returns, inflation

Percentage vs. Percentage Points

A short but important distinction that trips up news headlines, finance reports, and polling stories every day.

If an interest rate moves from 4% to 6%, that is a 2 percentage point increase but a 50% relative increase (2 ÷ 4 = 0.5). Mixing the two is one of the most common reporting errors in finance and politics — always check which one is meant.

Quick Reference Table

The percent-to-decimal-to-fraction conversions you'll reach for most often, in one scannable table.

PercentageDecimalFraction
10%0.101⁄10
12.5%0.1251⁄8
15%0.153⁄20
20%0.201⁄5
25%0.251⁄4
33.33%0.33331⁄3
50%0.501⁄2
75%0.753⁄4

Frequently Asked Questions

Quick answers to the questions people ask most about percentages and this calculator. Every answer here is mirrored in the page's FAQPage structured data for search engines.