Percentage Calculator

A percentage is a number or ratio expressed as a fraction of 100. The word "percent" comes from Latin: per centum. It means "by the hundred." Percentages appear everywhere in daily life — from discounts and tax rates to test scores and interest rates.

Our percentage calculator handles three types of calculations. Find a percentage of a number, determine what percentage one value represents of another, or reverse-calculate the whole from a known percentage. All three modes deliver answers quickly.

How to Use the Percentage Calculator

The calculator offers three modes to cover all common percentage problems:

Mode 1: What Is X% of Y?

Use this mode to find a percentage of any number. For example, "What is 20% of 500?" The answer is 100. This is the most commonly used percentage calculation — perfect for discounts, tips, tax amounts, and commissions.

Formula: Result = (X ÷ 100) × Y

Mode 2: X Is What Percent of Y?

Use this mode to find what percentage one number is of another. For example, "50 is what percent of 200?" The answer is 25%. This is useful for test scores, growth rates, and market share percentages.

Formula: Result = (X ÷ Y) × 100

Mode 3: X Is Y% of What?

Use this mode to reverse-calculate the whole number when you know a part and its percentage. For example, "25 is 50% of what?" The answer is 50. This is useful when you know the percentage amount but need to find the original total.

Formula: Result = (X × 100) ÷ Y%

Percentage Formula Explained

The core percentage formula is: Percentage = (Part ÷ Whole) × 100

The National Institute of Standards and Technology (NIST) recognizes percentages as a standardized way to express proportional relationships. They appear across all scientific and commercial fields.

Once you understand this basic formula, all percentage calculations become simple rearrangements:

• To find the part: Part = (Percentage ÷ 100) × Whole
• To find the whole: Whole = (Part ÷ Percentage) × 100
• To find the percentage: Percentage = (Part ÷ Whole) × 100

Common Percentage Calculations in Everyday Life

Calculating Discounts

When shopping, percentage discounts are everywhere. If a product costs $80 and is on sale at 25% off, you save $20 — making the final price $60. Our calculator makes these calculations instant. Simply enter the original price and the discount percentage to find your savings.

Calculating Tax

Sales tax is applied as a percentage of the purchase price. If an item costs $150 and the tax rate is 8%, the tax amount is $12, making the total $162. The same percentage logic applies to VAT, income tax, and other tax calculations.

Calculating Tips

When dining out, tipping is customary in many countries. A standard 15–20% tip on a $60 meal works out to $9–$12. Use the percentage calculator to get the exact tip amount. You can also use our dedicated Tip Calculator for detailed bill-splitting.

Interest Rates and Finance

Loans, credit cards, and savings accounts all use percentages. A 5% annual interest rate on a $10,000 deposit generates $500 in the first year. Understanding percentages is essential for smart financial decisions.

Test Scores and Grades

If you scored 72 out of 90 on a test, your score is 80% — calculated as (72 ÷ 90) × 100. This is the classic "X is what percent of Y" calculation used by students and educators worldwide.

Percentage Increase and Decrease

Percentage Increase: ((New Value − Old Value) ÷ Old Value) × 100

Percentage Decrease: ((Old Value − New Value) ÷ Old Value) × 100

For example, if a salary increased from $50,000 to $55,000, the percentage increase is 10%. For dedicated tools, try our Percentage Increase Calculator and Percentage Decrease Calculator.

Percent vs. Percentage Point

A percent is a relative measure, while a percentage point is an absolute difference between two percentages. If interest rates rise from 3% to 5%, that is a 2 percentage point increase but a 66.7% relative increase. This distinction is important in finance and statistics.

Tips for Working with Percentages

• Convert to decimals: 25% = 0.25, which is easier to multiply.
• Use the 10% trick: To find 10% of any number, move the decimal point one place left. 10% of 350 = 35. Double it for 20%; halve it for 5%.
• Check your work: After calculating, verify by working backwards to confirm correctness.
• Watch for asymmetry: Adding 10% then removing 10% does not return to the original number. These operations are not reversible.

Related Calculators

• Percentage Increase Calculator — Calculate how much something has grown
• Percentage Decrease Calculator — Calculate how much something has dropped
• Percentage Change Calculator — Find percentage change between two values
• Discount Calculator — Calculate sale prices and savings
• Tip Calculator — Calculate restaurant tips and split bills