How to Calculate Percentages

A complete guide to understanding and calculating percentages with practical examples.

What is a Percentage?

A percentage is a way of expressing a number as a fraction of 100. The word "percent" literally means "per hundred." For example, 50% means 50 out of 100, or half.

Basic Percentage Formula

The fundamental formula for calculating percentages is: 

Percentage = (Part ÷ Whole) × 100

Common Percentage Calculations

1. Finding What Percentage One Number Is of Another

Question: What percentage is 25 of 200?

Solution:
Step 1: Divide the part by the whole: 25 ÷ 200 = 0.125
Step 2: Multiply by 100: 0.125 × 100 = 12.5%
Answer: 25 is 12.5% of 200

2. Finding a Percentage of a Number

Question: What is 20% of 150?

Solution:
Step 1: Convert percentage to decimal: 20 ÷ 100 = 0.20
Step 2: Multiply by the number: 0.20 × 150 = 30
Answer: 20% of 150 is 30

3. Calculating Percentage Increase

Question: A price increased from R100 to R125. What's the percentage increase?

Solution:
Step 1: Find the difference: 125 - 100 = 25
Step 2: Divide by original: 25 ÷ 100 = 0.25
Step 3: Multiply by 100: 0.25 × 100 = 25%
Answer: The price increased by 25%

4. Calculating Percentage Decrease

Question: A product was R200, now it's R160. What's the discount percentage?

Solution:
Step 1: Find the difference: 200 - 160 = 40
Step 2: Divide by original: 40 ÷ 200 = 0.20
Step 3: Multiply by 100: 0.20 × 100 = 20%
Answer: The discount is 20%

Real-World Applications

Shopping Discounts: A store offers 30% off a R500 item. The discount amount is R150, so you pay R350.

Tax Calculations: If VAT is 15% and an item costs R100, the VAT is R15, making the total R115.

Grade Calculations: If you scored 42 out of 50 on a test, your percentage is 84%.

Financial Growth: If your investment grew from R10,000 to R12,000, that's a 20% increase.

Quick Tips for Mental Math

• 10%: Divide by 10 (move decimal point left one place)
• 5%: Find 10% and divide by 2
• 25%: Divide by 4
• 50%: Divide by 2
• 1%: Divide by 100

Use Our Calculators

Make these calculations instantly with our free tools:

• General Percentage Calculator
• Percentage Change Calculator
• What Percentage Is X of Y Calculator