MM → Inches
520 mm to inches
520 millimeters equals 20.472441 inches — or about 20 1/2" (nearest 1/16″).
Decimal
20.4724 in
Fraction
20 1/2"
Centimeters
52 cm
Feet
1.706 ft
mm
20.472441
in≈ 20 1/2" (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 = 520 ÷ 25.4 = 20.472441
Why 520 mm = 20.4724 in
Since 1 inch is defined as exactly 25.4 millimeters, 520 mm converts to 20.472441 inches. Rounded to the nearest 1/16″ that's 20 1/2", which is what you'd read off a standard imperial ruler.