MM → Inches
25.4 mm to inches
25.4 millimeters equals 1 inches — or about 1" (nearest 1/16″).
Decimal
1 in
Fraction
1"
Centimeters
2.54 cm
Feet
0.0833 ft
mm
1
in≈ 1" (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 = 25.4 ÷ 25.4 = 1
Why 25.4 mm = 1 in
Since 1 inch is defined as exactly 25.4 millimeters, 25.4 mm converts to 1 inches. Rounded to the nearest 1/16″ that's 1", which is what you'd read off a standard imperial ruler.