MM → Inches
20.5 mm to inches
20.5 millimeters equals 0.807087 inches — or about 13/16" (nearest 1/16″).
Decimal
0.8071 in
Fraction
13/16"
Centimeters
2.05 cm
Feet
0.0673 ft
mm
0.807087
in≈ 13/16" (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 = 20.5 ÷ 25.4 = 0.807087
Why 20.5 mm = 0.8071 in
Since 1 inch is defined as exactly 25.4 millimeters, 20.5 mm converts to 0.807087 inches. Rounded to the nearest 1/16″ that's 13/16", which is what you'd read off a standard imperial ruler.