How to Calculate Percentages: Formula & Daily-Life Examples

A percentage (%) is a fraction with a denominator of 100. It expresses a proportion of a whole and is used every day — discounts, interest, grades, and commissions.

Percentage Formulas

Percentage = (part ÷ whole) × 100

X% of a number = (X ÷ 100) × number

Examples

1. Scored 45 out of 60 → (45 ÷ 60) × 100 = 75%
2. 20% off 500 THB → (20 ÷ 100) × 500 = 100 THB
3. 250 THB increased by 10% → 250 + 25 = 275 THB

Increasing / Decreasing by a Percentage

• Increase by x%: number × (1 + x/100)
• Decrease by x%: number × (1 − x/100)

Example: salary 30,000 THB raised 5% → 30,000 × 1.05 = 31,500 THB

Where It Applies

• Discounts and promotions
• Deposit and loan interest
• Grades and exam scores
• Sales commissions

Try the percentage calculator to skip the manual math.