Percentage Calculator
Use this percentage calculator to find a percentage of a number, work out what percent one value is of another, or calculate percentage increase and decrease. Every answer shows the percentage formula used and the full working, so you can learn the method for exams — not just copy the result.
20% of 500 is 100
Step-by-step solution
- 20% of 500 = (20 ÷ 100) × 500
- = 0.2 × 500
- = 100
How to use the percentage calculator
- Choose what you want to calculate — for example "What is X% of Y?" or "Percentage change".
- Type the two numbers. The answer updates instantly as you type.
- Read the step-by-step working below the answer, or copy the link to share the exact calculation.
Formulas
| X% of Y | (X ÷ 100) × Y |
|---|---|
| What % is A of B | (A ÷ B) × 100 |
| Percentage change | ((New − Old) ÷ Old) × 100Positive = increase, negative = decrease. |
| Increase Y by X% | Y × (1 + X/100) |
| Decrease Y by X% | Y × (1 − X/100) |
Solved examples
Example 1: You scored 452 out of 500 in your board exams. What is your percentage?
- Percentage = (452 ÷ 500) × 100
- = 0.904 × 100
Answer: 90.4%
Example 2: A phone costing ₹15,000 becomes ₹18,000. By what percent did the price rise?
- Change = 18,000 − 15,000 = 3,000
- % change = (3,000 ÷ 15,000) × 100
Answer: 20% increase
Example 3: What is 18% GST on ₹2,450?
- 18% of 2,450 = (18 ÷ 100) × 2,450
Answer: ₹441
What does "percent" mean?
"Per cent" means "per hundred". Saying 35% is the same as saying 35 out of every 100, or the fraction 35/100, or the decimal 0.35. Because every percentage is out of the same base of 100, percentages make it easy to compare things of different sizes — like marks in two exams with different maximum marks.
To turn any fraction into a percentage, multiply it by 100. To turn a percentage back into a decimal, divide by 100. That single idea is behind every formula on this page.
Percentage shortcuts for competitive exams
Memorise common fraction–percent pairs: 1/2 = 50%, 1/3 = 33.33%, 1/4 = 25%, 1/5 = 20%, 1/6 = 16.67%, 1/8 = 12.5%, 1/9 = 11.11%, 1/10 = 10%. Aptitude questions in SSC, banking and placement tests are built around these values.
Use the multiplier method for successive changes: a 20% rise followed by a 10% fall is 1.20 × 0.90 = 1.08, a net 8% increase — not 10%. And note that X% of Y always equals Y% of X, so 8% of 50 is the same as 50% of 8 = 4.
🎯 Asked in competitive exams
This topic regularly appears in the quantitative aptitude section of:
- SSC CGL & CHSL
- IBPS & SBI PO / Clerk
- RRB NTPC
- Campus placement aptitude tests
AI resume builder, ATS score check and interview practice.
Frequently asked questions
What is the percentage formula?
Percentage = (Part ÷ Whole) × 100. To find X% of a number, use (X ÷ 100) × number; for percentage change, use ((New − Old) ÷ Old) × 100. For example, 45 out of 60 is (45 ÷ 60) × 100 = 75%.
How do I calculate the percentage of marks?
Divide the marks you scored by the total marks and multiply by 100. For example, 452 out of 500 is (452 ÷ 500) × 100 = 90.4%. Select "What % is A of B" in the calculator to do this instantly.
How do I calculate percentage increase?
Subtract the old value from the new value, divide the result by the old value, then multiply by 100. If the answer is negative it is a percentage decrease.
Is a 10% increase followed by a 10% decrease back to the original?
No. 100 increased by 10% is 110; 110 decreased by 10% is 99. The net effect is a 1% decrease, because the second 10% is taken on a larger number.
How do I find the original price before a percentage increase?
Divide the new price by (1 + rate/100). For example, if a price after an 18% increase is ₹1,180, the original price is 1,180 ÷ 1.18 = ₹1,000.
What is the difference between percentage and percentage points?
If an interest rate rises from 5% to 6%, it rose by 1 percentage point, but by 20 percent (because 1 is 20% of 5). News reports and exam questions often test this difference.
Keep learning
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