MM → Inches
18 mm to inches
18 millimeters equals 0.708661 inches — or about 11/16" (nearest 1/16″).
Decimal
0.7087 in
Fraction
11/16"
Centimeters
1.8 cm
Feet
0.0591 ft
mm
0.708661
in≈ 11/16" (nearest 1/16)
1 in = 25.4 mm · tolerance ±0.0001
Formula
To convert mm to inches, divide by 25.4:
inches = mm ÷ 25.4
inches = 18 ÷ 25.4 = 0.708661
Why 18 mm = 0.7087 in
Since 1 inch is defined as exactly 25.4 millimeters, 18 mm converts to 0.708661 inches. Rounded to the nearest 1/16″ that's 11/16", which is what you'd read off a standard imperial ruler.