MM → Inches
5.5 mm to inches
5.5 millimeters equals 0.216535 inches — or about 3/16" (nearest 1/16″).
Decimal
0.2165 in
Fraction
3/16"
Centimeters
0.55 cm
Feet
0.018 ft
mm
0.216535
in≈ 3/16" (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 = 5.5 ÷ 25.4 = 0.216535
Why 5.5 mm = 0.2165 in
Since 1 inch is defined as exactly 25.4 millimeters, 5.5 mm converts to 0.216535 inches. Rounded to the nearest 1/16″ that's 3/16", which is what you'd read off a standard imperial ruler.