How to Calculate Percentages: 5 Easy Methods with Examples

What is a Percentage?

A percentage (%) is a number expressed as a fraction of 100. "Per cent" literally means "per hundred." Percentages are used everywhere — sales discounts, exam scores, tax rates, interest rates, tips, and statistics.

Method 1: What is X% of Y?

The most common percentage calculation — for discounts, tips, and commissions.

Result = (X / 100) × Y

Example: What is 15% of $240?

Result = (15 / 100) × 240 = 0.15 × 240 = $36

Method 2: X is what % of Y?

Use this to find test scores, completion rates, and market share.

Percentage = (X / Y) × 100

Example: You scored 42 out of 60 on a test. What's your percentage?

Percentage = (42 / 60) × 100 = 0.7 × 100 = 70%

Method 3: Percentage Change (Increase or Decrease)

Use this to track price changes, stock returns, and growth rates.

% Change = ((New Value − Old Value) / Old Value) × 100

Example: A product went from $50 to $65. What's the percentage increase?

% Change = ((65 − 50) / 50) × 100 = (15 / 50) × 100 = 30%

Method 4: Find the Original Value

You know the final price after a discount — find the original.

Original = Final ÷ ((100 − discount%) / 100)

Example: After a 25% discount, a product costs $60. What was the original price?

Original = 60 ÷ (75 / 100) = 60 ÷ 0.75 = $80

Method 5: Add or Subtract a Percentage

Adding tax or a tip to a price.

New value = Original × (1 + percentage/100)
New value = Original × (1 − percentage/100)  [for decrease]

Example: Add 8% tax to a $120 item:

New value = 120 × 1.08 = $129.60

Mental Math Shortcuts

• 10%: Move the decimal point one place left (10% of 350 = 35)
• 5%: Half of 10% (5% of 350 = 17.5)
• 1%: Move the decimal point two places left (1% of 350 = 3.5)
• 25%: Divide by 4 (25% of 80 = 20)
• 50%: Divide by 2 (50% of 80 = 40)
• 20%: Divide by 5 (20% of 80 = 16)

Real-World Percentage Examples

• Shopping discount: 30% off $75 → 0.30 × 75 = $22.50 off = $52.50 final price
• Sales tax (8%): $100 item → 100 × 1.08 = $108
• Restaurant tip (18%): $60 bill → 0.18 × 60 = $10.80 tip
• Exam score: 38 correct out of 50 → (38/50) × 100 = 76%
• Interest rate: $1,000 at 5% annual → 1000 × 0.05 = $50 interest per year

Skip the manual calculation and use our free Percentage Calculator — calculate any percentage in seconds with three different calculation modes.