MM to Inches Calculator
Converting millimeters to inches is a common task for electricians and tradespeople who work with metric conduit specifications, imported fittings, or international blueprints. Since the US electrical trade primarily uses imperial measurements, having a quick and accurate conversion is essential for proper conduit sizing, box fill, and layout work.
This calculator converts any millimeter value to both decimal inches and the nearest 1/16-inch fraction. Simply enter the millimeter measurement and get the inch equivalent instantly. The fractional output is especially useful when marking conduit with a tape measure graduated in sixteenths.
MM to Inches Formula
Inches = Millimeters ÷ 25.4
1 inch = exactly 25.4 mm (international standard)
After obtaining the decimal inch result, the calculator also rounds to the nearest 1/16" fraction for practical field use. For example, 10 mm equals approximately 0.3937 inches, which rounds to 3/8" as the nearest common fraction.
Frequently Asked Questions
How do you convert millimeters to inches?
Divide the millimeter value by 25.4 to get inches. For example, 50.8 mm divided by 25.4 equals 2 inches. One inch is defined as exactly 25.4 millimeters.
What is the fractional inch equivalent of a millimeter value?
After converting mm to decimal inches, round to the nearest 1/16 inch for a standard fractional result. For example, 10 mm equals 0.3937 inches, which rounds to approximately 3/8 inch in common trade fractions.
Why do electricians need to convert mm to inches?
Many conduit fittings, tools, and specifications use metric measurements, while US electrical work primarily uses imperial units. Converting mm to inches ensures accurate conduit cuts, box fill calculations, and compliance with NEC requirements.