Millimeters and inches measure length. Millimeters are used in the metric system, while the inch is used in the imperial system. When converting between millimeters and inches, you need to know that there are 25.4 mm per inch. For example, if you were given a metric measurement in millimeters, you might need to convert it to an imperial measurement because inches are more commonly used than millimeters in the United States.
Divide 48 mm by 25.4 to convert to 1.89 inches.
Multiply 48 mm by 0.039370 to verify your conversion of 1.89 inches.
Check your millimeters-to-inches conversion with an online calculator (see Resources). Type in your distance in millimeters and press the "Go" button.