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Trying to figure out a tip, discount, or percentage change and math isn't your thing?

Calculate percentages instantly — percentage of, increase, decrease, and more.

Percentage Calculator

Calculate percentages, find what percent one number is of another, or measure percentage change

Understanding Percentages

A percentage is a way to express a number as a fraction of 100. The word comes from Latin “per centum” meaning “by the hundred.” Percentages are everywhere — discounts, tax rates, statistics, battery levels, and more. Understanding how they work helps you make better financial decisions.

Common Percentage Calculations

Three main types: (1) “X% of Y” — find a portion of a number (e.g., 15% of 200 = 30). (2) “X is what % of Y” — find what proportion one number is of another (e.g., 50 is 25% of 200). (3) “% change from X to Y” — find the percentage increase or decrease (e.g., price went from $80 to $100 = 25% increase).

Percentage Points vs Percent

These are commonly confused. If interest rises from 5% to 7%, that’s a 2 percentage point increase, but a 40% relative increase (2/5). Media reports often mix these up. Pay attention to which is being used.

Common Mistakes

  • ✗Confusing percentage increase with percentage of — a 50% increase on 100 is 150, not 50
  • ✗Adding percentages together incorrectly — 20% + 30% is not 50%
  • ✗Forgetting that percentages can exceed 100% when measuring change

Pro Tips

  • ✓Use the percentage change formula: ((new - old) / old) × 100
  • ✓To find what percentage X is of Y, divide X by Y and multiply by 100
  • ✓Double-check by working backwards from your result

Real-World Examples

Shopping discounts

A $80 jacket is 25% off — you pay $60

Grade calculations

You scored 18/20 on a test — that’s 90%

Battery life

Your phone went from 80% to 45% — a 35 percentage point drop

Formulas:

  • X% of Y = (X / 100) × Y
  • X is what % of Y = (X / Y) × 100
  • % Change = ((New - Old) / |Old|) × 100

Want to learn more?

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About Percentage Calculator

What is Percentage?

A percentage is a way to express a number as a fraction of 100. The word comes from the Latin “per centum,” meaning “by the hundred.” It is widely used in finance, statistics, science, and everyday calculations. Whether you are calculating a tip, determining a discount, measuring growth, or analyzing data, percentages provide a simple and standardized way to compare values and understand proportions.

For example, if 30 out of 200 students passed an exam, you can express this as 15%. This makes it easy to compare with other classes or exams regardless of the total number of students. Percentages are everywhere—interest rates, tax rates, exam scores, battery levels, weather forecasts, and more.

How to Calculate Percentages

There are three common percentage calculations you may need:

1. Finding X% of Y:Multiply Y by X/100. For example, 25% of 200 = (25/100) × 200 = 50. This is useful for calculating discounts, tips, or tax amounts.

2. Finding what percentage X is of Y:Divide X by Y and multiply by 100. For example, 50 is what percent of 200? (50/200) × 100 = 25%. This is useful for understanding proportions, such as what percentage of your budget is spent on rent.

3. Percentage change from X to Y:Subtract the old value from the new value, divide by the old value, and multiply by 100. For example, if a price went from $80 to $100, the change is ((100-80)/80) × 100 = 25% increase. This is commonly used in finance to track stock performance, revenue growth, or inflation.

This utility is provided for informational purposes only. KnowKit is not responsible for any errors in the output.

Frequently Asked Questions

How do I calculate a percentage increase?

Subtract the original value from the new value, divide by the original, then multiply by 100. Example: ($100 - $80) / $80 × 100 = 25% increase.

What's the difference between percentage and percentile?

A percentage is a proportion out of 100. A percentile indicates a position in a ranked dataset — if you're in the 90th percentile on a test, you scored higher than 90% of test-takers.

How do I calculate discount savings?

Multiply the original price by the discount percentage divided by 100. For a 20% discount on $50: $50 × 0.20 = $10 off. Your final price is $40.

Can a percentage be greater than 100?

Yes. If you invest $100 and get back $250, that's a 150% return. Percentages above 100 mean the result is more than the original amount.

How do you calculate percentage of a total in Excel?

Divide the part by the total and format as percentage. For example, if cell A1 has the part and B1 has the total, use =A1/B1 and apply percentage formatting. This works the same as (part/total) × 100.

What is the difference between percentage points and percent?

Percentage points measure the absolute difference between two percentages. If a tax rate goes from 5% to 8%, that's a 3 percentage point increase, but a 60% relative increase. Media and finance reports often distinguish between these.

How to calculate compound percentage change?

Multiply the growth factors together and subtract 1. For example, if something grows 10% then 20%, the total change is (1.10 × 1.20) - 1 = 0.32 = 32%, not 30%. This is why compound interest grows faster than simple interest.