1. The Basic Percentage Formula

A percentage is a way to express a number as a fraction of 100. The word "percent" means "per hundred."

Percentage = (Part ÷ Whole) × 100

Example: 45 students passed out of 60 total. What percentage passed?

  • Percentage = (45 ÷ 60) × 100 = 75%

2. Find a Percentage of a Number

Used for discounts, tax, interest — finding X% of any number.

Result = (Percentage ÷ 100) × Number

Examples:

  • 20% of 500 = (20 ÷ 100) × 500 = 100
  • 18% GST on ₹1,200 = (18 ÷ 100) × 1200 = ₹216
  • TDS at 10% on ₹50,000 = ₹5,000

🔢 Percentage Calculator

Calculate any percentage instantly — % of a number, percentage increase/decrease, what % is X of Y, and more.

Open Percentage Calculator →

3. Percentage Increase and Decrease

Used for price changes, salary hikes, inflation, population growth.

% Change = ((New − Old) ÷ Old) × 100

A positive result = increase. A negative result = decrease.

Examples:

  • Salary increased from ₹40,000 to ₹48,000: ((48,000 − 40,000) ÷ 40,000) × 100 = 20% increase
  • Price dropped from ₹2,500 to ₹2,000: ((2,000 − 2,500) ÷ 2,500) × 100 = −20% (20% decrease)

4. Calculate Discount Percentage

Used when shopping to find how much you saved.

Discount % = ((MRP − Sale Price) ÷ MRP) × 100

Example: A phone MRP is ₹20,000, on sale for ₹16,500.

  • Discount % = ((20,000 − 16,500) ÷ 20,000) × 100 = (3,500 ÷ 20,000) × 100 = 17.5% discount

Reverse (find sale price from discount %): Sale Price = MRP × (1 − Discount% ÷ 100)

  • 40% off on ₹5,000: 5,000 × (1 − 0.40) = ₹3,000

5. Percentage of Marks

The most searched percentage question in India — exam results.

Marks % = (Marks Obtained ÷ Total Marks) × 100

Examples:

Marks ObtainedTotal MarksPercentage
45060075%
38050076%
72090080%
31240078%

CGPA to percentage (under CBSE formula): Percentage ≈ CGPA × 9.5. So a 9.2 CGPA = approximately 87.4%.

6. Profit and Loss Percentage

Profit % = (Profit ÷ Cost Price) × 100
Loss % = (Loss ÷ Cost Price) × 100

Example: Bought a laptop for ₹45,000, sold for ₹52,000.

  • Profit = 52,000 − 45,000 = ₹7,000
  • Profit % = (7,000 ÷ 45,000) × 100 = 15.6%

7. What Percentage is X of Y?

Common question: "450 is what percent of 1,200?"

% = (X ÷ Y) × 100

(450 ÷ 1,200) × 100 = 37.5%

8. Reverse Percentage (Find Original Before % Was Applied)

If a price after 18% GST is ₹1,770, what was the original price?

Original = Final ÷ (1 + Rate ÷ 100)

1,770 ÷ 1.18 = ₹1,500

If a price after 15% discount is ₹425, what was the MRP?

425 ÷ (1 − 0.15) = 425 ÷ 0.85 = ₹500

9. Quick Percentage Reference Table

FractionPercentageDecimal
1/425%0.25
1/333.33%0.333
1/250%0.5
2/366.67%0.667
3/475%0.75
1/812.5%0.125
1/520%0.20

10. Frequently Asked Questions

What is the formula for percentage?
Percentage = (Part ÷ Whole) × 100. To find X% of a number: (X ÷ 100) × Number. To find percentage change: ((New − Old) ÷ Old) × 100.
How to calculate 20% of a number quickly?
Divide the number by 5. 20% of 350 = 350 ÷ 5 = 70. Or: 10% of a number = divide by 10; 20% = double the 10% value. 10% of 350 = 35; 20% = 70.
How to find percentage increase from old to new value?
% Increase = ((New Value − Old Value) ÷ Old Value) × 100. Example: from ₹80 to ₹100 = ((100 − 80) ÷ 80) × 100 = 25% increase.
How to calculate CGPA to percentage?
Under the CBSE formula: Percentage = CGPA × 9.5. A CGPA of 9.0 = 85.5%. Some universities use their own formula — check your institution's official conversion method.