MM → Inches
8 mm to inches
8 millimeters equals 0.314961 inches — or about 5/16" (nearest 1/16″).
Decimal
0.315 in
Fraction
5/16"
Centimeters
0.8 cm
Feet
0.0262 ft
mm
0.314961
in≈ 5/16" (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 = 8 ÷ 25.4 = 0.314961
Why 8 mm = 0.315 in
Since 1 inch is defined as exactly 25.4 millimeters, 8 mm converts to 0.314961 inches. Rounded to the nearest 1/16″ that's 5/16", which is what you'd read off a standard imperial ruler.