How to Calculate Percentage — Complete Formula Guide

Example 1: Test Score

1. 1You scored 72 out of 90 on a test.
2. 2Formula: (72 ÷ 90) × 100
3. 3Result: 80% — you scored 80%

Example 2: Sales Tax

1. 1Item costs $45, tax rate is 8%.
2. 2Tax amount: (8 ÷ 100) × 45 = $3.60
3. 3Total: $45 + $3.60 = $48.60

Example 3: Discount

1. 1Jacket was $120, now $84.
2. 2Discount: ((120 − 84) ÷ 120) × 100
3. 3Result: 30% discount

What is the basic percentage formula?

Percentage = (Part ÷ Whole) × 100. For example, if 30 out of 200 students passed, the pass rate is (30 ÷ 200) × 100 = 15%.

How do I calculate a percentage increase?

Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. If a price goes from $80 to $100, the increase is ((100 − 80) ÷ 80) × 100 = 25%.

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

Divide the first number by the second, then multiply by 100. Example: 45 is what % of 180? → (45 ÷ 180) × 100 = 25%.

How do I calculate a percentage of a number?

Multiply the number by the percentage divided by 100. Example: 15% of 200 = 200 × (15 ÷ 100) = 30.

What is the difference between percentage and percentage points?

A percentage point is an absolute difference between two percentages. If interest rates go from 3% to 5%, that's a 2 percentage point increase, but a 66.7% relative increase.