What Is a Percentage Calculator?
A percentage calculator helps you work out percentages without doing the math by hand. You enter two numbers, click Calculate, and get the answer instantly.
This tool has three calculators in one:
- What is X% of Y? Find a part of a number.
- X is what percent of Y? Find how big one number is compared to another.
- Percentage increase or decrease Find how much a value has gone up or down.
You can use it for discounts, taxes, marks, savings, price changes, and more.
How to Use the Percentage Calculator
1. Find a Percentage of a Number
Use the first calculator when you know the percentage and the total.
- Enter the percentage in the first box.
- Enter the number in the second box.
- Click Calculate.
Example: What is 20% of 150?
The answer is 30.
2. Find What Percent One Number Is of Another
Use the second calculator when you want to compare two numbers.
- Enter the part in the first box.
- Enter the total in the second box.
- Click Calculate.
Example: 30 is what percent of 120?
The answer is 25%.
3. Find Percentage Increase or Decrease
Use the third calculator to see how much something changed.
- Enter the old (starting) value in the first box.
- Enter the new (ending) value in the second box.
- Click Calculate.
Example: From 80 to 100.
The answer is a 25% increase.
Example: From 100 to 80.
The answer is a 20% decrease.
Use the copy button next to each result to copy the answer.
Percentage Formulas (With Simple Examples)
Knowing the formula helps you check any result yourself.
Formula 1: Percentage of a Number
Result = (Percentage ÷ 100) × Number
Example: 15% of 200
(15 ÷ 100) × 200 = 0.15 × 200 = 30
Formula 2: What Percent Is One Number of Another
Percentage = (Part ÷ Total) × 100
Example: 45 is what percent of 60?
(45 ÷ 60) × 100 = 0.75 × 100 = 75%
Formula 3: Percentage Change
Percentage Change = ((New Value − Old Value) ÷ Old Value) × 100
- A positive result means an increase.
- A negative result means a decrease.
Example: A phone price goes from ₹20,000 to ₹23,000.
((23,000 − 20,000) ÷ 20,000) × 100 = 15% increase
Real-Life Uses of Percentages
Shopping and Discounts
A jacket costs ₹2,000 and has a 15% discount.
- Discount = 15% of 2,000 = ₹300
- Final price = 2,000 − 300 = ₹1,700
Tax and GST
An item costs ₹1,000 and GST is 18%.
- GST = 18% of 1,000 = ₹180
- Total price = ₹1,180
Exam Marks
You scored 432 out of 600.
- (432 ÷ 600) × 100 = 72%
Salary Hikes
Your salary rises from ₹40,000 to ₹44,000.
- ((44,000 − 40,000) ÷ 40,000) × 100 = 10% increase
Tips and Service Charges
A restaurant bill is ₹1,500 and you want to leave a 10% tip.
- 10% of 1,500 = ₹150
Business and Profit
A shop buys an item for ₹500 and sells it for ₹650.
- ((650 − 500) ÷ 500) × 100 = 30% profit on cost
How to Find the Original Price After a Discount
Sometimes you only know the final price and the discount. In that case, the original price is:
Original Price = Final Price ÷ (1 − Discount ÷ 100)
Example: A shirt costs ₹800 after a 20% discount.
- 1 − 0.20 = 0.80
- 800 ÷ 0.80 = ₹1,000
The original price was ₹1,000.
Quick Mental Math Tricks
You can estimate common percentages in your head.
- 10%: Move the decimal one place left. 10% of 250 = 25.
- 5%: Take half of 10%. 5% of 250 = 12.5.
- 1%: Move the decimal two places left. 1% of 250 = 2.5.
- 50%: Divide by 2.
- 25%: Divide by 4.
- 15%: Add 10% and 5%. 15% of 250 = 25 + 12.5 = 37.5.
Quick Reference Table (Percentages of 250)
| Percentage | Result |
|---|---|
| 1% | 2.5 |
| 5% | 12.5 |
| 10% | 25 |
| 25% | 62.5 |
| 50% | 125 |
| 75% | 187.5 |
| 100% | 250 |
Common Percentage Mistakes to Avoid
Mixing Up the Old and New Value
In percentage change, always divide by the old value. If you divide by the new value, your answer will be wrong.
Thinking Increase and Decrease Are Equal
A 50% increase followed by a 50% decrease does not bring you back to the start.
- Start: 100
- After a 50% increase: 150
- After a 50% decrease: 75
The second change is applied to a bigger number, so the result is lower than where you began.
Confusing Percentage and Percentage Points
If an interest rate goes from 5% to 7%:
- It rose by 2 percentage points.
- It rose by 40 percent, because 2 ÷ 5 = 0.40.
These are different measures, so use the right term.
Starting From Zero
You cannot calculate a percentage change from a starting value of 0. Dividing by zero has no valid answer.
Frequently Asked Questions
How do I calculate a percentage of a number?
Divide the percentage by 100, then multiply by the number. For 12% of 500: 0.12 × 500 = 60.
Can a percentage be more than 100%?
Yes. If a value more than doubles, the increase is over 100%. For example, going from 50 to 150 is a 200% increase. Also, 150 is 300% of 50.
What does a negative percentage change mean?
It means the value went down. For example, a change of −20% means a 20% decrease.
How do I find the percentage difference between two numbers?
Use the percentage change formula. Subtract the old value from the new value, divide by the old value, then multiply by 100.
Is 0.5 the same as 50%?
Yes. To change a decimal into a percentage, multiply by 100. To change a percentage into a decimal, divide by 100.
How do I add a percentage to a number?
Multiply the number by (1 + percentage ÷ 100). To add 12% to 500: 500 × 1.12 = 560.
How do I subtract a percentage from a number?
Multiply the number by (1 − percentage ÷ 100). To subtract 12% from 500: 500 × 0.88 = 440.
Is this percentage calculator free?
Yes. You can use it as many times as you like with no sign-up.
Final Thoughts
Percentages are part of everyday life, from sale prices to salary changes. This calculator gives you quick, correct answers, and the formulas and examples above help you understand how the numbers work. Bookmark this page so you have it ready the next time you need a percentage.