Finance & CalculatorsOctober 20, 2026 2 min read

How to Calculate Percentage: Formulas, Percentage Change and Discounts

Easy percentage formulas with examples — find X% of a number, percentage increase or decrease, marks percentage and discounts.

Percentages show up in marks, discounts, taxes, salary hikes and interest rates. Four formulas cover nearly everything.

1. X% of a number

Result = number × X ÷ 100. Example: 15% of 2,400 = 2,400 × 15 ÷ 100 = 360.

Percent = A ÷ B × 100. Example: you scored 432 out of 600 → 432 ÷ 600 × 100 = 72%.

Change % = (new − old) ÷ old × 100. Example: salary from ₹40,000 to ₹46,000 → 6,000 ÷ 40,000 × 100 = 15% increase.

Discount = price × discount% ÷ 100; final price = price − discount. Example: ₹2,500 with 20% off → discount ₹500, you pay ₹2,000.

Percentage Calculator

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How do I calculate 20% of a number?

Multiply the number by 20 and divide by 100 — or multiply by 0.2.

How do I calculate percentage increase?

Subtract the old value from the new one, divide by the old value, then multiply by 100.

How do I convert marks into a percentage?

Divide marks obtained by total marks and multiply by 100.