Height & length conversions

Convert between inches, feet, centimetres, and metres for height-dependent calculations.

What is this for?

Height feeds body surface area, ideal body weight, and BMI. Charted heights are recorded inconsistently — feet and inches in one system, centimetres in another — and a mis-keyed height propagates silently into every downstream dose.

How to use it

Enter the measurement and its unit.
Pick the destination unit.
For a height recorded as feet and inches, convert the total inches (for example 5 ft 9 in = 69 in).

Worked example

A patient is 5 ft 9 in tall. Express the height in centimetres for a Mosteller BSA calculation.

Answer: 5 ft 9 in = 69 in; 69 × 2.54 = 175.26 cm.

Clinical pearls & pitfalls

The inch is defined as exactly 2.54 cm, so unlike the volume and weight conventions this conversion carries no approximation.
When calculating ideal body weight, work in total inches over 60 (5 feet), not in feet-and-inches — mixing the two is a frequent source of error.
A height entered in centimetres into a field expecting inches produces an implausibly large BSA. Sanity-check BSA against the 1.5–2.0 m² range typical of adults.

Assumptions & limitations

Converts length only; it does not validate that the value is a plausible human height. Check the result yourself.
Self-reported heights are systematically over-reported, particularly in older adults, which biases BSA and IBW upward.

References

International yard and pound agreement, 1959: 1 inch ≡ 2.54 cm exactly.
National Institute of Standards and Technology. Handbook 44, Appendix C: General Tables of Units of Measurement.