What is 20% of 15? 3 20% of 15 Copy 20% of 15 = 3. Formula UsedResult = (20 ÷ 100) × 15 = 3 Frequently Asked Questions What is 20% of 15?3. (20 ÷ 100) × 15 = 3.How to calculate 20%?Multiply by 0.2 (or multiply by 20 then divide by 100).