What is 50% of 40? 20 50% of 40 Copy 50% of 40 = 20. Formula UsedResult = (50 ÷ 100) × 40 = 20 Frequently Asked Questions What is 50% of 40?20. (50 ÷ 100) × 40 = 20.How to calculate 50%?Multiply by 0.5 (or multiply by 50 then divide by 100).