What is 8% of 40? 3.2 8% of 40 Copy 8% of 40 = 3.2. Formula UsedResult = (8 ÷ 100) × 40 = 3.2 Frequently Asked Questions What is 8% of 40?3.2. (8 ÷ 100) × 40 = 3.2.How to calculate 8%?Multiply by 0.08 (or multiply by 8 then divide by 100).