How to Calculate a Percentage: 6 Simple Formulas with Examples
Quick answer: To find a percentage of an amount, multiply the amount by the percentage and divide by 100. Example: 15% of 2,400 = 2,400 × 15 ÷ 100 = 360. To find what percent one number is of another, divide the part by the whole and multiply by 100: 450 ÷ 1,500 × 100 = 30%.
Use the percentage and discount calculator →
The 6 percentage formulas
| You want | Formula | Example |
|---|---|---|
| A percentage of an amount | amount × % ÷ 100 | 2,400 × 15 ÷ 100 = 360 |
| What percent A is of B | A ÷ B × 100 | 450 ÷ 1,500 × 100 = 30% |
| Percentage increase | (new − old) ÷ old × 100 | (8,600 − 8,000) ÷ 8,000 × 100 = 7.5% |
| Percentage decrease | (old − new) ÷ old × 100 | (250 − 200) ÷ 250 × 100 = 20% |
| Price after a discount | price × (100 − %) ÷ 100 | 400 × 70 ÷ 100 = 280 |
| Price before a discount | sale price ÷ (100 − %) × 100 | 240 ÷ 80 × 100 = 300 |
1. Percentage of an amount
Multiply the amount by the percentage, then divide by 100. A salary of 9,000 SAR with a 10% bonus: 9,000 × 10 ÷ 100 = 900 SAR.
2. What percent one number is of another (between two numbers)
Divide the part by the whole and multiply by 100. If you spent 1,200 SAR of a 4,800 SAR budget: 1,200 ÷ 4,800 × 100 = 25%.
3. Percentage of grades (exam results)
Divide your marks by the total marks and multiply by 100. A student with 432 out of 480: 432 ÷ 480 × 100 = 90%.
4. Percentage increase and decrease
Take the difference, divide it by the old value, then multiply by 100. A salary that goes from 8,000 to 8,600 SAR rose by 7.5%. A price that drops from 250 to 200 SAR fell by 20%. Always divide by the old value, not the new one.
5. Discount percentage
If a product was 500 SAR and now costs 350 SAR, the discount is (500 − 350) ÷ 500 × 100 = 30%. To find the price after a 30% discount on 400 SAR: 400 × 70 ÷ 100 = 280 SAR, so you save 120 SAR.
6. Finding the original price
If you paid 240 SAR after a 20% discount, the original price was 240 ÷ 80 × 100 = 300 SAR. The same idea removes VAT from a price: divide by 1.15. See how to calculate 15% VAT.
Quick tricks without a calculator
- 10%: move the decimal point one place left. 10% of 3,450 = 345.
- 5%: half of 10%. 5% of 3,450 = 172.5.
- 25%: divide by 4. 25% of 3,200 = 800.
- 50%: divide by 2.
- 1%: move the decimal point two places left, then multiply for any whole percent.
Open the percentage and discount calculator →
Frequently asked questions
How do I calculate a percentage of an amount?
Multiply the amount by the percentage and divide by 100. Example: 20% of 750 = 750 × 20 ÷ 100 = 150.
How do I find the percentage between two numbers?
Divide the smaller part by the whole and multiply by 100. Example: 45 out of 60 = 45 ÷ 60 × 100 = 75%.
How do I calculate a percentage increase?
Subtract the old value from the new one, divide by the old value and multiply by 100. From 200 to 230 is a 15% increase.
How do I calculate the discount percentage?
Subtract the sale price from the original price, divide by the original price and multiply by 100. From 500 to 350 is a 30% discount.
How do I calculate my grade percentage?
Divide your marks by the total marks and multiply by 100. 432 out of 480 is 90%.
This guide explains the general rules. It is not legal advice.