Feet and Inches to Meters

How the feet-and-inches to meters conversion works

The calculator takes two inputs — a whole number of feet and a fractional or whole number of inches — combines them into a single decimal-foot value, then multiplies by the exact factor 0.3048 to produce meters. The formula is: m = (ft + in/12) × 0.3048. From the meter result, centimeters are derived by multiplying by 100 and millimeters by multiplying by 1,000. All three outputs are exact for the values entered; no rounding is introduced in the arithmetic itself, only in the displayed precision.

The exact conversion factor

One foot equals exactly 0.3048 meters. This is a defined constant, not a measurement — it was fixed by the international yard and pound agreement of 1959, which set 1 yard = 0.9144 m and therefore 1 foot = 0.3048 m and 1 inch = 0.0254 m exactly. Because both factors are definitions rather than approximations, the conversion from any feet-and-inches value to meters carries zero rounding error in the factor itself. The only figures that affect accuracy are the feet and inches entered.

What the secondary outputs show

Alongside meters (shown to four decimal places), the calculator displays centimeters (two decimal places), millimeters (whole number), and decimal feet (four decimal places). Centimeters and millimeters are the units most likely to appear on metric engineering drawings, tile layouts, and imported fixtures; decimal feet is useful when feeding the result into a spreadsheet or formula that expects a single numeric value rather than a split feet-inches pair.

Worked examples

A standard 8 ft 0 in ceiling height equals exactly 2.4384 m (243.84 cm, 2,438 mm). A person 5 ft 6 in tall is 1.6764 m (167.64 cm, 1,676 mm). A 1 ft reference length is 0.3048 m (30.48 cm, 305 mm). Each result follows directly from the factor — (8 + 0/12) × 0.3048 = 2.4384, (5 + 6/12) × 0.3048 = 1.6764, (1 + 0/12) × 0.3048 = 0.3048.

Where feet and inches appear in US construction

US residential and light-commercial construction uses feet and inches almost universally for plan dimensions, ceiling and door heights, framing layouts, and lumber lengths. Dimensional lumber is sold and specified in nominal inch sizes (2×4, 2×6) with actual dimensions also in inches. When working alongside metric specifications — imported windows or doors, European appliances, metric engineering drawings, or international project documentation — dimensions need converting to meters or millimeters. The same need arises when a US-trained contractor reads a metric detail sheet, or when a metric-trained professional interprets a US plan.

Common dimension conversions in practice

Standard US door heights run from 6 ft 8 in (2.0320 m) to 8 ft 0 in (2.4384 m). A 4 ft 0 in sheet width (plywood, drywall) is 1.2192 m. A 10 ft 0 in room width is 3.0480 m. A 16 in on-center stud spacing is 0.4064 m. These relationships are used frequently enough that they are worth committing to memory, but the calculator handles any arbitrary feet-and-inches value instantly.

The feet-inches split and decimal feet

US plans often annotate dimensions as, for example, 5'-6" — the apostrophe for feet and the double-quote for inches. The decimal-feet equivalent of 5 ft 6 in is 5.5000 ft, since 6 in is exactly half a foot. Not all splits produce round decimals: 5 ft 7 in is 5.5833 ft (repeating), so the feet-and-inches notation preserves precision that a decimal-feet rounding would lose. The calculator displays decimal feet to four places to capture this.

Precision and rounding in the results

The calculator displays meters to four decimal places, which gives a resolution of 0.1 mm — more than adequate for any construction dimension. Millimeters are shown as whole numbers because sub-millimeter resolution exceeds the practical tolerance of field measurement (typically ±1 mm with a steel tape). Centimeters are shown to two decimal places (0.01 cm = 0.1 mm) for compatibility with metric drawing annotations. For ultra-precise machining or survey work, the full decimal representation is available by carrying the meter value to more decimal places in a separate calculation.

Using this alongside other BuildMetricLab tools

Once a dimension is in meters it feeds directly into area and volume calculators — room area in square meters, concrete volume in cubic meters, or tile coverage in square meters. The cubic yards to cubic meters calculator handles volume conversions, and the square feet to square meters calculator converts plan areas. All BuildMetricLab tools run entirely in the browser — no sign-up, no data sent anywhere, and the formula is shown on the page so the math can be audited.