To convert 42 millimeter to inch, multiply by the conversion factor 0.039370. So, 42 mm x 0.039370 = 1.65354 inch. For practical purposes, this is often rounded to 1.6535 inch.

42 millimeter equals exactly 1.653543307 inch. For practical purposes, this is often rounded to 1.6535 inch.

Objects measuring approximately 42 millimeter include a 42mm diameter watch case (e.g., Tissot PRX 42mm), a 42mm diameter micro speaker used in compact audio devices, and a 42mm precision pin gauge for industrial calibration.

Converting millimeter to inch is useful for international collaboration, interpreting engineering blueprints from countries using imperial units, ensuring compatibility with tools and parts manufactured to different standards, and for general understanding in regions where inches are the primary unit of measurement.

Memory aids and shortcuts for converting 42 millimeter to inch include remembering that 1mm is roughly 0.04 inches (so 42 x 0.04 = 1.68 inches), or visualizing a common 42mm object like a watch face to internalize the size.