Feet to Millimeters Converter

Feet to Millimeters

Convert feet (ft) to millimeters (mm). Both measure distance and dimension, and the conversion comes up in construction, navigation, sports work.

The Formula

`` millimeters = feet × 304.8 feet = millimeters × 0.00328083989501 `

One foot is 304.8 millimeters, and one millimeter is 0.003281 feet.

Conversion Table

Feet	Millimeters
1 ft	304.8 mm
2 ft	609.6 mm
5 ft	1,524 mm
10 ft	3,048 mm
25 ft	7,620 mm
50 ft	15,240 mm
100 ft	30,480 mm
500 ft	152,400 mm
1,000 ft	304,800 mm

The Other Direction

Millimeters	Feet
1 mm	0.003281 ft
2 mm	0.006562 ft
5 mm	0.016404 ft
10 mm	0.032808 ft
25 mm	0.082021 ft
50 mm	0.164042 ft
100 mm	0.328084 ft
500 mm	1.6404 ft
1,000 mm	3.2808 ft

What Each Unit Is

Feet (ft) — exactly 0.3048 metres, or one third of a yard. A human foot, standardised across centuries of conflicting local definitions.

Millimeters (mm) — one thousandth of a metre. The metric unit engineering drawings default to, because it removes decimal points from most dimensions.

A Sense of Scale

• A ceiling is 8–9 ft
• Aviation altitude is always in feet
• A door is about 6.7 ft
• A credit card is 0.76 mm thick
• A paperclip wire is about 1 mm
• Rainfall is measured in mm

Precision

The factor 304.8 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const footToMillimeter = (value) => value * 304.8; ``

Where This Conversion Comes Up

• Construction
• Navigation
• Sports
• Sewing
• Mapping

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 ft with the factor truncated at each decimal place:

Decimals kept	Factor	137 ft becomes	Error
0	305	41,785	0.0656%
1	304.8	41,757.6	—
2	304.8	41,757.6	—
3	304.8	41,757.6	—
4	304.8	41,757.6	—

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured feet to three significant figures, the answer in millimeters is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From Feet

The same value in every other unit this converter supports for length:

From	To	Unit
1 ft	0.3048 m	Meters
1 ft	3.0480e-4 km	Kilometers
1 ft	30.48 cm	Centimeters
1 ft	1.8939e-4 mi	Miles
1 ft	0.333333 yd	Yards
1 ft	12 in	Inches
1 ft	1.6458e-4 nmi	Nautical Miles

Chaining conversions works — feet to metres to feet gives the same answer as feet to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.