Calcufast

Online Percentage Calculator

Calculate percentages quickly: find the percentage of a number, calculate percentage changes, and apply increases or discounts

Calculator
Select the operation you want to perform

What is X% of Y?

Result

You may also like

Complete Guide to Percentages

What are percentages?

Percentages are a way of expressing a proportion or fraction as a quantity out of 100. The symbol "%" means "per cent" or "out of every 100". Percentages are used constantly in daily life: store discounts, interest rates, statistics, grades, and much more.

Understanding how to calculate percentages allows you to make better financial decisions, compare offers, and understand statistical data more clearly.

Formulas for each operation

1. Percentage of a number

Result = (Percentage / 100) × Amount

2. What percentage one quantity is of another

Percentage = (Part / Total) × 100

3. Percentage change

Change % = ((Final Value - Initial Value) / Initial Value) × 100

4. Apply increase or discount

With increase: Result = Value × (1 + Percentage/100) With discount: Result = Value × (1 - Percentage/100)

Practical examples

Example 1: Store discount

A product costs $150 and has a 20% discount. The discount is: (20/100) × 150 = $30. The final price is: 150 - 30 = $120. Alternatively: 150 × (1 - 0.20) = $120.

Example 2: Salary increase

If your salary of $2,000 increases by 15%, the raise is: (15/100) × 2000 = $300. Your new salary will be: 2000 + 300 = $2,300.

Frequently asked questions

To calculate X% of a number Y, multiply Y by X and divide by 100. For example, 15% of 200 is (200 × 15) / 100 = 30. You can also multiply directly: 200 × 0.15 = 30.

Percentage change is calculated by subtracting the initial value from the final value, dividing by the initial value, and multiplying by 100. If a product went from $80 to $100, the change is ((100-80)/80) × 100 = 25% increase.

An increase adds the percentage to the original value, while a discount subtracts it. For 20% on $100: increase = $120, discount = $80. The formula uses (1 + p/100) for increases and (1 - p/100) for discounts.

If you know the discounted price and the percentage applied, divide the final price by (1 - discount/100). For example, if you paid $80 with a 20% discount: $80 ÷ 0.80 = $100 was the original price.

Sales tax is applied to the net price because it's a percentage of the product's value before taxes. If a product costs $100 + 8% tax, the tax is $8 and the total is $108. Tax is not calculated on itself.

Common mistakes when calculating percentages

Avoid these errors

  1. Confusing the percentage base: A 50% increase followed by a 50% decrease does NOT return you to the original value. $100 + 50% = $150, then $150 - 50% = $75.

  2. Adding percentages directly: Two 10% discounts don't equal 20%. The first reduces to $90, the second reduces to $81 (19% total).

  3. Forgetting to convert to decimal: 15% = 0.15, not 15. A common calculator error.

Related calculators

Explore other useful tools for your calculations: