MM → Inches
25.5 mm to inches
25.5 millimeters equals 1.003937 inches — or about 1" (nearest 1/16″).
Decimal
1.0039 in
Fraction
1"
Centimeters
2.55 cm
Feet
0.0837 ft
mm
1.003937
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 = 25.5 ÷ 25.4 = 1.003937
Why 25.5 mm = 1.0039 in
Since 1 inch is defined as exactly 25.4 millimeters, 25.5 mm converts to 1.003937 inches. Rounded to the nearest 1/16″ that's 1", which is what you'd read off a standard imperial ruler.