Feet to Meters

The Exact Conversion Factor: 1 ft = 0.3048 m

This page converts feet to meters using the single exact factor 0.3048, no approximations, no rounding of the multiplier. That number is not arbitrary: it comes directly from the 1959 international agreement that defined 1 inch = 25.4 mm exactly. Because 1 foot = 12 inches, the math is simple:

1 ft = 12 × 25.4 mm = 304.8 mm = 0.3048 m.

Before 1959 the United States, the United Kingdom, and other Commonwealth countries each used slightly different foot lengths. The international foot (0.3048 m) ended that confusion for most purposes. A separate unit, the U.S. survey foot (1 ft = 1200/3937 m ≈ 0.3048006 m), survives in some American land‑surveying records, but this calculator uses the international definition — the standard in science, engineering, and nearly all international commerce.

The inverse relationship is equally exact:

1 m = 1 / 0.3048 ft ≈ 3.28083989501 ft.

That long decimal never repeats because 1 / 0.3048 is an irrational number when expressed in base 10, but the factor itself is exact. If you ever need to reverse the conversion, multiply meters by 3.28083989501 to get feet.

How This Calculator Works – No Approximations

Many quick‑reference tools multiply feet by 0.305 or round the result to two decimals. This page does neither. The algorithm is trivial but strict:

output_meters = input_feet × 0.3048

No extra rounding, no truncation before the final display. The default output shows six decimal places, but the internal calculation preserves full double‑precision floating‑point value. That means:

• Zero input → exactly 0 m.
• Negative input → linear result. Example: –10 ft → –3.048 m.
• Very large numbers → standard floating‑point representation; a value like 1 000 000 ft yields 304 800 m exactly (no scientific notation unless the number exceeds normal display limits).
• Non‑numeric input (letters, symbols, empty box) → an error message appears, and no conversion is performed.

Because the factor is a terminating decimal (0.3048), the product is always accurate to within machine precision. There is no hidden approximation.

Common Approximations Versus Precision

The common “rule of thumb” conversion — 1 ft ≈ 0.3 m — is off by 0.0048 m per foot, a relative error of about 1.6 %. That may be fine for estimating a room’s size in your head, but it fails in situations where tolerances are tight:

In construction, a 3.84 cm error on a ceiling height can require re‑cutting drywall or altering door frames. In aviation, 168 m of altitude error is dangerous. The exact factor eliminates those risks.

Worked Examples for Real‑World Use

Height conversion – A person who is 5 ft 10 in tall. First convert inches to decimal feet: 10 in ÷ 12 = 0.83333… ft. Add to 5 ft → 5.83333 ft. Multiply by 0.3048:

5.83333 × 0.3048 = 1.777999... m

Rounded to three decimals: 1.778 m. (In many medical and athletic contexts, height is given to the nearest 0.01 m, so 1.78 m is sufficient.)

Room dimensions – A room 12 ft × 10 ft:

• 12 ft → 12 × 0.3048 = 3.6576 m
• 10 ft → 10 × 0.3048 = 3.048 m

Area: 3.6576 m × 3.048 m = 11.148 m² (exact). A quick‑and‑dirty factor of 0.3 would give 3.6 m × 3.0 m = 10.8 m², an error of 0.348 m².

Sports distances – A 20‑ft long jump:

20 × 0.3048 = 6.096 m

Track and field records are measured in meters (and centimeters); the exact conversion matters for comparing imperial‑era records to modern metric ones.

Handling Edge Cases – Decimal, Negative, and Fractional Inputs

This calculator accepts decimal input directly: type 3.5 for 3 ½ ft or 0.3048 for 1 in. There is no separate field for inches; the user must convert inches to decimal feet before typing. (Example: 5 ft 6 in → 6 in ÷ 12 = 0.5 ft → enter 5.5.)

Negative values are handled correctly. If you need to convert a depth below a reference plane, e.g., –50 ft → –15.24 m, the tool returns a negative result with the same absolute‑value precision.

Very large and very small numbers – Floating‑point arithmetic introduces tiny rounding at extreme scales (beyond 10^15 or below 10^−15), but you are unlikely to encounter those values in everyday use. For a number like 1 000 000 000 ft, the result is 304 800 000 m — exact in standard double precision.

Fractions – The tool does not parse fractions like “3 1/2”. Enter 3.5 instead. If you have a mixed number, convert it: 7 ¼ ft = 7.25 ft.

Why the Exact Factor Matters – Historical and Practical Context

The 1959 definition was adopted to align measurements across the Atlantic. Before that:

• The U.S. foot was based on the Mendenhall order of 1893, where 1 ft = 1200/3937 m ≈ 0.304800601 m.
• The British Imperial foot was defined by the Weights and Measures Act of 1878; after 1959 the UK adopted 0.3048 m as well.

Today, the international foot (0.3048 m) is used for all non‑surveying applications in the United States: aviation altitudes (feet to meters for international flight plans), engineering drawings that involve metric components, and consumer goods (e.g., lumber dimensions often list both feet and meters). Surveyors in some U.S. states still use the survey foot for legal property boundaries — a discrepancy of 2 parts per million. This calculator uses the international foot, the standard for everything except those specific cadastral systems.

Exactly because the factor is a neat decimal, the conversion is linear and reversible without loss. If you ever need to chain units — say, feet → meters → centimeters — you can multiply by 0.3048 and then by 100, or work through inches (1 ft → 12 in → 25.4 mm → 0.0254 m). All paths lead to the same number because the inch definition anchors everything.

FAQ

1. Why is the conversion factor exactly 0.3048?
Because the international inch was defined as exactly 25.4 mm in 1959. Since 1 ft = 12 in, 1 ft = 12 × 25.4 mm = 304.8 mm = 0.3048 m exactly. This eliminated pre‑1959 variations.

2. Can I use this page to convert meters to feet?
No. The tool works strictly feet → meters. To convert the other way, multiply your meters by the inverse factor 3.28083989501 (or 1/0.3048) and use a separate calculator.

3. What if I enter a fraction like 5 1/2?
The input box expects a plain decimal number. Convert the fraction first: 5 ½ = 5.5. The tool will then compute correctly.

4. Does the tool round its result?
The multiplication itself uses the exact factor with no rounding. The displayed result shows a default number of decimal places (typically six), but the underlying value is not truncated. If you need more digits, the full floating‑point result is available if your browser displays it.

5. Why does my result sometimes show a long decimal like 1.8288?
Because 0.3048 is a four‑decimal number, the product often extends to four or more decimal places. For example, 6 ft = 1.8288 m exactly; 7 ft = 2.1336 m exactly. These are not approximations — they are the precise values. You may round the display yourself for practical use.

6. How does this relate to the U.S. survey foot?
The international foot (0.3048 m) differs from the U.S. survey foot (0.304800601 m) by about 2 × 10⁻⁶ m. This tool uses the international definition, which is correct for 99.9% of applications. Only land surveying in certain U.S. states requires the survey foot.