Posted in Web How big is 30 mm in inches? – Answers March 16, 2026 30mm is 1.1811 inches.Direct Conversion Formula 30 mm*1 in25.4 mm=1.181102362 inThere are 2.54 centimeters in an inch and 10 mm in a cm. That gives you 1.1811 inches. https://www.answers.com/general-science/How_big_is_30_mm_in_inches