MM → Inches
508 mm to inches
508 millimeters equals 20 inches — or about 20" (nearest 1/16″).
Decimal
20 in
Fraction
20"
Centimeters
50.8 cm
Feet
1.6667 ft
mm
20
in≈ 20" (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 = 508 ÷ 25.4 = 20
Why 508 mm = 20 in
Since 1 inch is defined as exactly 25.4 millimeters, 508 mm converts to 20 inches. Rounded to the nearest 1/16″ that's 20", which is what you'd read off a standard imperial ruler.