How to Convert 20mm to Inches
20 mm ÷ 25.4 = 0.7874 inches. To find the nearest 32nd, multiply by 32: 0.7874 × 32 = 25.2, which rounds to 25/32.
On a Tape Measure
Standard US tape measures show marks at every 1/16 inch. The nearest mark to 20mm is the 13/16″ mark. For rough layout work, use the 3/4″ mark.