How do you calculate percentage of a number?

To find P% of a number X, multiply the number by the percentage and divide by 100: Result = (P × X) / 100. For example, 18% of 500 = (18 × 500) / 100 = 90.

How do you calculate percentage increase or decrease?

Percentage Change = ((New Value - Old Value) / |Old Value|) × 100. If positive, it is a percentage increase; if negative, it is a percentage decrease.

How do you find what percentage one number is of another?

To find what percentage X is of Y: Percentage = (X / Y) × 100. For example, 45 out of 60 is (45 / 60) × 100 = 75%.

Percentage Calculator — Calculate % of Number, % Change & Difference

How to Calculate Percentages: 5 Essential Formulas

Percentages express a ratio or fraction as a fraction of 100 (from Latin per centum, meaning 'by the hundred'). Whether you are calculating retail discounts, GST/tax rates, salary hikes, or test exam scores, here is how each percentage formula works.

1. Percentage of a Number (P% of X)

Result = (P × X) / 100

Example: What is 18% GST on ₹2,500? → (18 × 2500) / 100 = ₹450.

2. What % is X of Y?

Percentage = (X / Y) × 100

Example: Scored 420 out of 500 in exam? → (420 / 500) × 100 = 84%.

3. Percentage Change (% Increase / Decrease)

% Change = [(New - Old) / Old] × 100

Example: Price went from ₹80 to ₹100? → [(100 - 80) / 80] × 100 = +25% increase.

4. Increase / Decrease by P%

New Value = X × (1 ± P / 100)

Example: ₹50,000 salary with 12% appraisal → 50,000 × 1.12 = ₹56,000.

Common Percentage Conversions Reference

Percentage	Decimal	Fraction	Quick Calculation Trick
5%	0.05	1/20	Divide by 20, or find 10% and halve it
10%	0.10	1/10	Move the decimal one place to the left
12.5%	0.125	1/8	Divide by 8
20%	0.20	1/5	Divide by 5
25%	0.25	1/4	Divide by 4 (half of a half)
33.33%	0.333...	1/3	Divide by 3
50%	0.50	1/2	Divide by 2
75%	0.75	3/4	Divide by 4, then multiply by 3

Frequently Asked Questions

How do I calculate percentage difference between two numbers?

Percentage difference = (|Value 1 - Value 2| / Average of both values) × 100. It is used when neither number is specifically the 'original' starting point.

Why is a 50% loss not recovered by a 50% gain?

Because percentages are calculated relative to the base value. If you start with ₹100 and lose 50%, you have ₹50. A 50% gain on ₹50 is only ₹25, leaving you with ₹75. You need a 100% gain to recover from a 50% loss.