4.2 millimeters (mm) to inches (in)

4.2 millimeters = 0.16535442 inches

To convert 4.2 millimeters to inches, divide 4.2 millimeters by the conversion factor 25.4 (since 1 millimeter equals 1/25.4 inches).

The conversion formula is :
inches = millimeters ÷ 25.4

Here's the calculation to convert 4.2 mm to in :
4.2 millimeters ÷ 25.4 = 0.16535442 inches

Therefore, 4.2 millimeters is equal to 0.16535442 inches

A millimeter is a unit of length in the International System of Units (SI), equal to one thousandth of a meter. It is abbreviated using the symbol mm (e.g. 4.2 mm).

An inch is a unit of length in the British imperial and US customary systems of measurement. It is defined as exactly 2.54 centimeters. The inch is abbreviated using the symbols in or " (e.g. 0.16535442 in or 0.16535442").