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Percentage Calculator

Calculate percentages instantly for free.

What is% of=
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X is what percent of Y?
is what percent of=
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Percentage increase / decrease
Fromto=
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Results update as you type.

Quick reference
QuestionFormula
What is X% of Y?(X ÷ 100) × Y
X is what percent of Y?(X ÷ Y) × 100
Find the whole amountX ÷ (P ÷ 100)
Percentage increase((new − old) ÷ old) × 100
Percentage decrease((old − new) ÷ old) × 100
Percentage difference(|A − B| ÷ average) × 100

What is a percentage?

A percentage is a way of expressing a number as a fraction of 100. The word itself means "per hundred". So 50% means 50 out of 100, 25% means 25 out of 100, and 100% means the full amount.

Percentages are useful because they let you compare values in a simple, standard way. Instead of saying one value is 0.4 of another, you can say it is 40% — easier to read, easier to compare, and easier to use in everyday life.

Example: 20 out of 50 students are left-handed.

20 ÷ 50 × 100 = 40%

The answer is 40%.

How to calculate a percentage

The basic percentage formula is:

(part ÷ whole) × 100 = percentage

This works when you know the part and the whole, and you want to know how large the part is as a percentage of the whole.

15 people out of 60 bought a product:

15 ÷ 60 × 100 = 25%

So 15 is 25% of 60.

What is X percent of a number?

The most common percentage question — used for discounts, tips, tax, and everyday maths.

(X ÷ 100) × Y = result

What is 20% of 150?

0.20 × 150 = 30

20% of 150 is 30.

Percentage increase

Percentage increase shows how much a value has gone up relative to the original. Use it when comparing prices, salaries, follower counts, or any growing metric.

((new value − original value) ÷ original value) × 100

A price changes from 80 to 100:

((100 − 80) ÷ 80) × 100 = 25%

The price increased by 25%.

Percentage decrease

Percentage decrease shows how much a value has gone down relative to the original. Useful for markdowns, losses, and any shrinking metric.

((original value − new value) ÷ original value) × 100

A price changes from 100 to 85:

((100 − 85) ÷ 100) × 100 = 15%

The price decreased by 15%.

Percentage difference

Percentage difference compares two values using their average as the base. It is useful when neither value is clearly the "original" — for example, comparing two prices, two scores, or two groups.

(|value A − value B| ÷ average of A and B) × 100

Compare 10 and 6:

Difference = 4  ·  Average = 8

4 ÷ 8 × 100 = 50%

The percentage difference is 50%.

Real-life uses for percentage calculations

🛒 Shopping & discounts
Find the discount amount and final price after a percentage off.
🍽️ Tips & service charges
Calculate a tip quickly without mental gymnastics.
🧾 Tax & VAT
Work out tax on a product or service, or reverse-calculate the pre-tax amount.
📊 Business & marketing
Growth rates, conversion rates, engagement, margins, and period-over-period changes.
📝 Grades & scores
Turn a raw score into a percentage to understand performance.
💹 Finance & investments
Show price movements, returns, profit, and losses in relative terms.

Common mistakes to avoid

Forgetting to multiply by 100
Dividing the part by the whole gives a decimal. Multiply by 100 to convert it into a percentage.
Mixing up increase and decrease
When a value rises, use the percentage increase formula. When it falls, use percentage decrease. Using the wrong one flips the meaning.
Using the wrong base number
Percentage change is always relative to the starting value. Doubling from 50 to 100 is a 100% increase — not 50%.
Rounding too early
Keep decimals until the final step to avoid compounding rounding errors, especially in multi-step calculations.
Shopping or comparing prices?
The Discount Calculator is built for this — calculate sale price, amount saved, original price, or discount percentage directly.
Try it →
Frequently asked questions
What is the easiest way to calculate a percentage?
Divide the part by the whole and multiply by 100. For example, 20 out of 50 is 20 ÷ 50 = 0.4, and 0.4 × 100 = 40%.
How do I calculate 20 percent of a number?
Convert 20% to 0.20 and multiply by the number. For example, 20% of 150 is 0.20 × 150 = 30.
How do I find what percentage one number is of another?
Divide the first number by the second, then multiply by 100. For example, 25 out of 200 is (25 ÷ 200) × 100 = 12.5%.
How do I calculate percentage increase?
Subtract the original value from the new value, divide by the original value, and multiply by 100. Increasing from 80 to 100 gives a 25% increase.
How do I calculate percentage decrease?
Subtract the new value from the original, divide by the original, and multiply by 100. Decreasing from 100 to 85 gives a 15% decrease.
What is the difference between percentage change and percentage difference?
Percentage change measures movement from one value to another (you need a clear starting point). Percentage difference compares two values using their average, with no implied direction.
Can I use this calculator for discounts?
Yes. Enter the discount percentage and the original price in the 'What is X% of Y?' section to get the discount amount. Subtract that from the original price to get the final price.
Can I use this calculator for tips or VAT?
Yes. The same percentage-of-a-number formula works for tips, sales tax, and VAT calculations.
Why is my result a decimal?
Many percentage calculations produce decimals, especially when numbers do not divide evenly. That is normal — round the result if needed.
How do I reverse a percentage to find the original number?
Use the 'Find the whole amount' section. Enter the part and the percentage, and the calculator works out the original number. The formula is: part ÷ (percentage ÷ 100).
What is 100% of a number?
100% of any number is the number itself. 100% means the full amount.
What is the percentage increase from 0?
A percentage increase from zero is undefined because division by zero is not possible. Percentage change always requires a non-zero starting value.