MM → Inches
16.5 mm to inches
16.5 millimeters equals 0.649606 inches — or about 5/8" (nearest 1/16″).
Decimal
0.6496 in
Fraction
5/8"
Centimeters
1.65 cm
Feet
0.0541 ft
mm
0.649606
in≈ 5/8" (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 = 16.5 ÷ 25.4 = 0.649606
Why 16.5 mm = 0.6496 in
Since 1 inch is defined as exactly 25.4 millimeters, 16.5 mm converts to 0.649606 inches. Rounded to the nearest 1/16″ that's 5/8", which is what you'd read off a standard imperial ruler.