Ft to Mm Converter: Convert Feet to Millimeters

How to use the feet to mm converter

1. Enter a value in the Feet field to convert ft to mm, or enter a value in the Millimeters field to convert the other way.
2. The result updates automatically as you type.
3. Use the output for construction plans, engineering drawings, or any task that requires switching between imperial and metric lengths.

How the conversion works

The relationship between feet and millimeters is defined through the international yard and pound agreement of 1959, which set one foot to exactly 0.3048 meters. Since one meter contains 1,000 millimeters, one foot equals exactly 304.8 millimeters.

To convert feet to millimeters, multiply by 304.8:

mm = ft x 304.8

For example, 6 feet: 6 x 304.8 = 1,828.8 mm.

To convert millimeters to feet, divide by 304.8:

ft = mm / 304.8

For example, 1,000 mm: 1000 / 304.8 = 3.280839895... ft. Because 304.8 is an exact decimal, converting from feet to millimeters never introduces rounding error. Converting from millimeters to feet may produce a repeating decimal, which this tool rounds to 12 significant digits.

Common ft to mm values

This table lists frequently used conversions from feet to millimeters. Each value is exact because the factor 304.8 terminates after one decimal place.

When you need feet to millimeters

Drafting and CNC machining often require dimensions in millimeters even when the original plans are drawn in feet and inches. A single misplaced decimal can ruin a part, so using a reliable ft to mm converter matters on the shop floor.

In architecture, building codes in some countries specify tolerances in millimeters while site measurements arrive in feet. Converting accurately ensures compliance without manual arithmetic errors.

Model makers and 3D printing enthusiasts also switch between systems. A miniature scaled from a real-world structure measured in feet needs precise millimeter values for the printer's slicer software.

If you also need to work with centimeters, see the cm to m converter or the cm to feet page for related calculations.

Related unit conversions

Feet and millimeters sit at different scales within their respective systems. One foot is about a third of a meter, while a millimeter is one thousandth of a meter. Bridging that gap means multiplying by a relatively large number.

For larger distances, you might convert miles to feet first, then apply the 304.8 factor. For metric-only work, feet to meters divides by 3.28084 instead.

If your measurement includes inches, convert the total to inches first (one foot equals 12 inches), then use the fact that one inch is exactly 25.4 mm. Alternatively, add the inch portion converted to mm directly to the feet portion converted to mm.

Precision and rounding notes

The factor 304.8 is exact under NIST Special Publication 811 and the international yard definition. There is no approximation involved when going from feet to millimeters.

Going from millimeters to feet, however, involves dividing by 304.8. The result is often a non-terminating decimal. For instance, 1 mm equals approximately 0.00328083989501 feet. This tool displays up to 12 significant digits, which is more than sufficient for engineering tolerances. If you need fewer digits, round the output to suit your application.

Negative values are supported. A negative length has no physical meaning in most contexts, but the arithmetic remains valid for coordinate differences or offsets.

Worked examples