Percentage Calculator Free Online

Free online percentage calculator. Calculate what percent of a number is, find percentage increase/decrease, and more.

What is X% of Y?
What is% of=—
X is what % of Y?
is what % of=—
% change from X to Y
Fromto=—
X increased/decreased by Y%
% =—

Quick reference

  • X% of Y = (X/100) × Y
  • X is what % of Y = (X/Y) × 100
  • % change = ((New-Old)/Old) × 100
  • Increase/Decrease = X × (1 ± Y/100)

Percentage calculations come up constantly in everyday life - working out sale discounts, calculating VAT or sales tax, understanding investment returns, figuring out tips at restaurants, or interpreting statistics in news and research. Despite how common they are, percentage calculations trip up many people. This free percentage calculator handles all the most common percentage questions instantly, showing both the formula and the result so you understand how the answer was reached.

How to Use the Percentage Calculator

1

Choose the calculation type

Select which type of percentage calculation you need: "What is X% of Y?" (for finding a percentage of a number), "X is what percentage of Y?" (for finding the percentage relationship between two numbers), "Percentage change from X to Y" (for finding increase or decrease), or "X% increase/decrease of Y" (for applying a percentage change).

2

Enter your values

Input the relevant numbers for your chosen calculation type. The input fields are labelled clearly to show what each value represents. You do not need to include the % symbol - just enter the number.

3

Read the result and formula

The answer appears instantly with the full formula shown, so you can verify the calculation and understand the method. You can adjust the values and the result updates in real time.

Percentage Formulas Explained

Finding X% of a number - multiply the number by the percentage divided by 100. Formula: Result = (Percentage ÷ 100) × Number. Example: 15% of 240 = (15 ÷ 100) × 240 = 0.15 × 240 = 36. Use this for: calculating a discount amount, finding a percentage share, working out VAT/tax on a price.

Finding what percentage X is of Y - divide X by Y and multiply by 100. Formula: Percentage = (X ÷ Y) × 100. Example: What percentage is 36 of 240? = (36 ÷ 240) × 100 = 0.15 × 100 = 15%. Use this for: finding a score as a percentage, calculating market share, expressing a portion as a percentage of the whole.

Percentage increase/decrease - subtract the original from the new value, divide by the original, and multiply by 100. Formula: Change % = ((New - Original) ÷ Original) × 100. A positive result is an increase; negative is a decrease. Example: Price went from 80 to 100. Change = ((100 - 80) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% increase. Use this for: comparing prices, tracking growth rates, measuring performance changes.

Applying a percentage increase or decrease - multiply the original by (1 + percentage/100) for an increase, or by (1 - percentage/100) for a decrease. Example: 20% increase on £80 = 80 × 1.20 = £96. Example: 15% discount on £200 = 200 × 0.85 = £170.

Common Everyday Percentage Calculations

Shopping discounts - a 30% discount on a £120 item: 120 × 0.30 = £36 discount, so you pay £120 - £36 = £84. Or: 120 × 0.70 = £84 (paying 70% of the original price).

VAT and sales tax - adding 20% VAT to a price of £50: 50 × 1.20 = £60. Removing 20% VAT from a VAT-inclusive price of £60: 60 ÷ 1.20 = £50 (not 60 × 0.80 = £48, which is a common mistake).

Tips at restaurants - 15% tip on a £45 bill: 45 × 0.15 = £6.75 tip; total = £51.75. 20% tip: 45 × 0.20 = £9 tip; total = £54.

Investment returns - if an investment grows from £10,000 to £12,500: percentage return = ((12,500 - 10,000) ÷ 10,000) × 100 = (2,500 ÷ 10,000) × 100 = 25% return.

Frequently Asked Questions

What percentage calculations does the calculator support?
The calculator supports four main calculation types: (1) What is X% of Y - finding a percentage of a number; (2) X is what % of Y - finding the percentage relationship between two numbers; (3) Percentage change from X to Y - calculating percentage increase or decrease; (4) Applying a percentage increase or decrease to a number. The tool shows the formula used for each calculation alongside the result.
How do I calculate a percentage discount?
To find the discount amount: multiply the original price by the discount percentage divided by 100. Example: 25% off £80 = 80 × (25/100) = 80 × 0.25 = £20 discount. To find the final price after discount: multiply the original price by (1 minus the discount as a decimal). Example: 80 × (1 - 0.25) = 80 × 0.75 = £60. Use the "What is X% of Y?" calculation type for the discount amount, or the "Percentage decrease" type for the final price.
How do I calculate percentage change between two numbers?
The formula is: ((New Value - Original Value) ÷ Original Value) × 100. A positive result means an increase; a negative result means a decrease. Example: Sales went from 250 to 300: ((300 - 250) ÷ 250) × 100 = (50 ÷ 250) × 100 = 20% increase. Example: Temperature dropped from 20°C to 15°C: ((15 - 20) ÷ 20) × 100 = (-5 ÷ 20) × 100 = -25% (a 25% decrease).
What is the formula for percentage?
The basic percentage formula is: Percentage = (Part ÷ Whole) × 100. For example, if you scored 45 out of 60 on a test: (45 ÷ 60) × 100 = 75%. To reverse (find the part from a percentage): Part = (Percentage ÷ 100) × Whole. Example: 30% of 200 = (30 ÷ 100) × 200 = 0.30 × 200 = 60.
Why is removing VAT different from calculating a discount?
This is a common source of confusion. If a price of £100 has 20% VAT added, you get £120 (£100 × 1.20). To remove the VAT to get back to £100, you divide by 1.20 (£120 ÷ 1.20 = £100). If you instead subtracted 20% (£120 × 0.80 = £96), you get a different (wrong) answer. That is because 20% of £120 (£24) is different from 20% of £100 (£20). Always divide by (1 + tax rate) to remove tax from an inclusive price.