What is 4% of 40? 1.6 4% of 40 Copy 4% of 40 = 1.6. Formula UsedResult = (4 ÷ 100) × 40 = 1.6 Frequently Asked Questions What is 4% of 40?1.6. (4 ÷ 100) × 40 = 1.6.How to calculate 4%?Multiply by 0.04 (or multiply by 4 then divide by 100).