Percentage Calculator - Free Online Calculator

How to Use

Choose calculation type
Select from percentage of a number, percentage change, or discount calculation.
Enter values
Input the required numbers for your chosen calculation type.
View result
Click Calculate to see the percentage result instantly.

What Is a Percentage?

A percentage (%) expresses a part of a whole when the whole is taken as 100. The term 'per cent' comes from Latin and means 'per hundred', so 25% is the same as 25 out of 100, or 0.25. Because it is more intuitive than fractions or decimals, percentages are widely used to compare values of different sizes on a common scale.

Percentage problems usually fall into three types.

Finding the rate: what percentage one number is of a whole (e.g. 32 correct out of 40 questions → 80%)
Finding the part: what a given percentage of a whole equals (e.g. the amount of a 15% discount off the list price)
Percentage change: how much a value has grown or shrunk relative to its original (e.g. stock prices, revenue)

Discounts, sales tax, interest rates, growth rates, attendance rates, pass rates and nearly every comparison metric in daily life and business are expressed as percentages.

Formulas

These are the three core formulas this calculator supports.

Finding the part: part = whole × percent ÷ 100
e.g. 15% of 200 → 200 × 15 ÷ 100 = 30
Finding the rate: percent = part ÷ whole × 100
e.g. 32 ÷ 40 × 100 = 80%
Percentage change: change = (new value − original value) ÷ |original value| × 100
e.g. 100 → 130 : (130 − 100) ÷ 100 × 100 = +30%

Here the 'whole' is the reference value, the 'part' is the value being compared, and the 'original value' is the value before the change. If the denominator is 0, the percentage is undefined.

Frequently Asked Questions

How do I calculate a percentage?

The formula depends on the type. (1) 'What is Y% of X?' → X × Y ÷ 100, (2) 'X is what % of Y?' → X ÷ Y × 100, (3) 'percentage change from X to Y' → (Y − X) ÷ |X| × 100. This calculator supports all three modes.

What is B% of A?

Calculate it as A × B ÷ 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. You get the same result by converting the percentage to a decimal (15% → 0.15) and multiplying.

How do I calculate percentage increase?

Use (new value − old value) ÷ old value × 100. For example, going from 100 to 130 is a 30% increase. A negative result means the value decreased by that amount.

What is the difference between a percent (%) and a percentage point (%p)?

A percent is a relative ratio, while a percentage point is the absolute difference between two percent values. For example, if an interest rate rises from 3% to 5%, that is a 2 percentage point rise (absolute difference), but as a growth rate it is (5 − 3) ÷ 3 × 100 ≈ 66.7% (relative change).

How do I calculate the price after a discount?

Use original price × (1 − discount ÷ 100). For example, a 20% discount on a $50 item gives 50 × 0.8 = $40. If you only want the discount amount, it is 50 × 0.2 = $10.

Can I work backward from a discounted price to the original (list) price?

Yes. Original price = discounted price ÷ (1 − discount ÷ 100). For example, if an item costs $56 after a 30% discount, then 56 ÷ 0.7 = $80 is the list price.

Is applying a percentage twice the same as just adding them?

No. Raising 100 by 20% and then by another 10% gives 100 × 1.2 × 1.1 = 132, a 32% increase, not the simple sum of 30%. Likewise, raising and then lowering by the same rate does not return the original value: 100 → +50% → 150 → −50% → 75.

How do I convert a fraction or decimal to a percentage?

For a decimal, multiply by 100 (0.375 × 100 = 37.5%). For a fraction, divide the numerator by the denominator and multiply by 100 (3/8 = 0.375 → 37.5%). To convert a percentage back to a decimal, divide by 100 (37.5% → 0.375).

Verified 2026 formulas

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