What is a percentage?

A percentage is a way of expressing a number as a fraction of 100. The word 'percent' comes from the Latin 'per centum', meaning 'by the hundred'. For example, 25% means 25 out of every 100, or 0.25 as a decimal.

How do I calculate what percent X is of Y?

Divide X by Y, then multiply by 100. For example, to find what percent 15 is of 60: (15 ÷ 60) × 100 = 25%. Use the 'X is what percent of Y?' calculator on this page for instant results.

What is the difference between percentage change and percentage difference?

Percentage change measures how much a value has increased or decreased from a starting point — it has a direction (increase or decrease). Percentage difference measures the relative difference between two values without implying a direction — it's the absolute difference divided by the average of the two values, expressed as a percentage.

Can I calculate a percentage of a negative number?

Yes. The calculators on this page accept negative numbers. For example, 20% of -500 is -100, and the percentage change from -80 to -100 is -25% (a decrease). The formulas work correctly for negative inputs.

What does 'percentage increase' mean?

A percentage increase tells you by how much a value has grown relative to its original value. Formula: ((New Value − Original Value) ÷ Original Value) × 100. For example, a price rising from 80 to 100 is a 25% increase because (100 − 80) ÷ 80 × 100 = 25.

Is this calculator accurate?

Yes. All calculations are performed using standard floating-point arithmetic in JavaScript and display up to 10 significant figures. For everyday percentage calculations the results are exact. Very large numbers (above 10^15) may have minor floating-point rounding, which the tool flags with a warning.

Percentage Calculator

Calculate percentages instantly. Find what percent one number is of another, calculate percentage increase or decrease, and more — all free, no signup required.

What is X% of Y?

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X is what percent of Y?

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Percentage Increase / Decrease Calculator

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Increase / Decrease a Number by a Percentage

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Percentage Difference Between Two Numbers

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What is X% More / Less Than Y?

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How to Calculate Percentages

Finding a percentage of a number

Multiply the number by the percentage, then divide by 100. Example: 20% of 500 = (20 × 500) ÷ 100 = 100.

Finding what percentage X is of Y

Divide X by Y, then multiply by 100. Example: 15 is what % of 60? → (15 ÷ 60) × 100 = 25%.

Percentage increase or decrease

Subtract original from new, divide by the original, multiply by 100. Example: 80 → 100 = ((100 − 80) ÷ 80) × 100 = 25% increase.

Percentage difference

Divide the absolute difference by the average of the two values, then multiply by 100. Example: difference between 40 and 60 = |40−60| ÷ ((40+60)÷2) × 100 = 40%.

Why use our online Percentage Calculator?

Solve common percentage problems instantly — find what % one number is of another, calculate discounts, markup, percentage change, and more without a separate app.

How to use Percentage Calculator

1
Choose a calculator type
Scroll to the section that matches what you need — finding a percentage of a number, calculating percentage change, finding percentage difference, and more.
2
Enter your numbers
Type values into the input fields. Results update in real time as you type — no need to press a button.
3
Read the formula
Below each result, you'll see the exact formula used (e.g. '(20 ÷ 100) × 500 = 100') so you understand the math.
4
Expand step-by-step explanation
Click 'Show steps' under any result to see a plain-English breakdown of the calculation — useful for learning or double-checking your work.
5
Copy the result
Click the copy button next to any result to copy the answer to your clipboard instantly.

Percentage calculations everyone needs — and keeps forgetting

Four percentage problems come up constantly in daily life, and most people have to look up the formula every time.

"What is X% of Y?" Multiply Y by X and divide by 100. 20% of 85 = (85 × 20) / 100 = 17. Mental shortcut: 10% of any number is just move the decimal one place left. 10% of 85 = 8.5. Double it for 20% = 17.

"X is what percent of Y?" Divide X by Y and multiply by 100. 17 is what percent of 85? (17 / 85) × 100 = 20%. Mental shortcut: flip the division — if the relationship is simple (like 1/4 = 25%), recognize it immediately.

"What is the percentage increase from A to B?" (B − A) / A × 100. Price rose from $80 to $100: (100 − 80) / 80 × 100 = 25% increase.

"What was the original value before a percentage increase?" Divide the new value by (1 + rate/100). Item costs $120 after a 20% increase: 120 / 1.2 = $100 original price. This is the reverse percentage calculation — commonly needed for tax-inclusive prices.

Percentage change vs percentage point change — a critical distinction

Percentage change and percentage point change are two different measurements that are frequently confused, often deliberately in misleading statistics.

A percentage point change is the arithmetic difference between two percentages. If a bank's savings rate rises from 3% to 5%, it increased by 2 percentage points (5 − 3 = 2).

A percentage change measures the relative change. The same rate increase is a 66.7% increase relative to the original: (5 − 3) / 3 × 100 = 66.7%.

The confusion is regularly exploited in media and marketing. "Our interest rate doubled!" sounds dramatic (100% increase in percentage terms) when the rate went from 0.5% to 1.0% — a change of only 0.5 percentage points, which is barely noticeable in practice. Conversely, describing a drop in unemployment from 10% to 8% as "down 2 points" understates the relative improvement (which is 20%).

The rule: always check which type of change is being reported. For interest rates, tax rates, and other measurements that are already expressed as percentages, percentage point change is usually more meaningful.

Discounts, markups, and tips — percentage math in everyday shopping

Retail percentages follow predictable patterns once you understand the underlying arithmetic.

Discount: A 30% discount on a $150 item means you pay 70% of the original price. 150 × 0.70 = $105. Mental shortcut: subtract 30% by finding 30% (150 × 0.30 = 45) and subtracting: 150 − 45 = 105.

Markup: retailers apply markup as a percentage of their cost. A product costing $40 with a 150% markup sells for $40 + (40 × 1.5) = $40 + $60 = $100. Note the asymmetry: a 150% markup is not a 150% gross margin. Gross margin = (Revenue − Cost) / Revenue = (100 − 40) / 100 = 60%.

Tax-inclusive pricing: if a $89.99 price tag includes 8% sales tax, the pre-tax price is 89.99 / 1.08 = $83.32. The tax portion is $89.99 − $83.32 = $6.67.

Tipping in restaurants: the easiest mental arithmetic method is to calculate 10% (move decimal left), then adjust. For an $82 bill: 10% = $8.20. A 20% tip = $16.40. A 15% tip = $8.20 + $4.10 = $12.30 (15% = 10% + half of 10%).

Frequently Asked Questions

What is a percentage?: A percentage is a way of expressing a number as a fraction of 100. The word 'percent' comes from the Latin 'per centum', meaning 'by the hundred'. For example, 25% means 25 out of every 100, or 0.25 as a decimal.
How do I calculate what percent X is of Y?: Divide X by Y, then multiply by 100. For example, to find what percent 15 is of 60: (15 ÷ 60) × 100 = 25%. Use the 'X is what percent of Y?' calculator on this page for instant results.
What is the difference between percentage change and percentage difference?: Percentage change measures how much a value has increased or decreased from a starting point — it has a direction (increase or decrease). Percentage difference measures the relative difference between two values without implying a direction — it's the absolute difference divided by the average of the two values, expressed as a percentage.
Can I calculate a percentage of a negative number?: Yes. The calculators on this page accept negative numbers. For example, 20% of -500 is -100, and the percentage change from -80 to -100 is -25% (a decrease). The formulas work correctly for negative inputs.
What does 'percentage increase' mean?: A percentage increase tells you by how much a value has grown relative to its original value. Formula: ((New Value − Original Value) ÷ Original Value) × 100. For example, a price rising from 80 to 100 is a 25% increase because (100 − 80) ÷ 80 × 100 = 25.
Is this calculator accurate?: Yes. All calculations are performed using standard floating-point arithmetic in JavaScript and display up to 10 significant figures. For everyday percentage calculations the results are exact. Very large numbers (above 10^15) may have minor floating-point rounding, which the tool flags with a warning.

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