Inch to Millimeter

Minimal, fast, and accurate. Type a value, select units, get the result instantly.

Type a number to convert instantly.

Result

25.4

mm

Conversion rate: 1 in = 25.4 mm

Showing up to 4 decimal

How it works

The converter uses exact SI-based factors (e.g., 1 foot = 0.3048 meters, 1 inch = 0.0254 meters).

Formula: millimeters = inch × 25.4

Results show between 0 and 8 decimal places and hide trailing zeros for readability.

Conversion Table

Inch Millimeter
0.001 in 0.0254 mm
0.01 in 0.254 mm
0.1 in 2.54 mm
1 in 25.4 mm
10 in 254 mm
100 in 2540 mm
1000 in 25400 mm

History

Inch (in)

The inch, abbreviated as in, is a length unit in the imperial and US customary systems. Its history reaches back to ancient civilizations, including the Romans, Egyptians, and Anglo-Saxons. Originally, the inch was determined by the width of a human thumb, but it was eventually set as 1/12 of a foot. Since 1959, the inch has been officially defined as exactly 2.54 centimeters due to an international agreement. Inches are still widely used in the United States, Canada, and the UK, especially for construction, manufacturing, and personal measurements. Even with the global shift to metric units, the inch remains important in certain fields such as technical drawings, screen dimensions, and household tools.

Millimeter (mm)

The millimeter, abbreviated mm, stands for one-thousandth of a meter and is crucial for precise measurement tasks. Introduced with the metric system in the late 1700s, the millimeter allows for extremely detailed measurements, which is why it is vital in engineering, machining, and manufacturing. Its precision helps create parts that fit perfectly together. The millimeter is also commonly used in science, including microscopy, material studies, and building construction. Although it measures a tiny length, the millimeter has played a major role in enhancing accuracy and global measurement standards.

Other Relevant Conversions

m → cm m → mm m → km m → in m → ft m → yd m → mi m → µm m → nm cm → m cm → mm cm → km cm → in cm → ft cm → yd cm → mi cm → µm cm → nm mm → m mm → cm mm → km mm → in mm → ft mm → yd mm → mi mm → µm mm → nm km → m km → cm km → mm km → in km → ft km → yd km → mi km → µm km → nm in → m in → cm in → mm in → km in → ft in → yd in → mi in → µm in → nm ft → m ft → cm ft → mm ft → km ft → in ft → yd ft → mi ft → µm ft → nm yd → m yd → cm yd → mm yd → km yd → in yd → ft yd → mi yd → µm yd → nm mi → m mi → cm mi → mm mi → km mi → in mi → ft mi → yd mi → µm mi → nm µm → m µm → cm µm → mm µm → km µm → in µm → ft µm → yd µm → mi µm → nm nm → m nm → cm nm → mm nm → km nm → in nm → ft nm → yd nm → mi nm → µm