4/20 as a Decimal 0.2 4/20 = 0.2 = 20% Copy 4/20 = 0.2 = 20%. Simplified: 1/5. Formula Used4 ÷ 20 = 0.2 Frequently Asked Questions What is 4/20 as a decimal?0.2.What is 4/20 as a percentage?20%.