To convert 18mm to inches, you can use the conversion factor of 1 inch equals 25.4mm. Therefore, 18mm is approximately 0.71 inches (18 mm ÷ 25.4 mm/inch). On a ruler, you would find 0.71 inches …
https://www.answers.com/natural-sciences/Where_is_18mm_to_inches_on_a_ruler

