The inch has been exactly 2.54 centimetres since 1959
There is no approximation hiding in this conversion. In 1959 the inch was redefined internationally as exactly 2.54 cm, which makes one foot exactly 30.48 cm. So a height in feet and inches converts to a single exact decimal in centimetres — and the answer is a definition, not a measurement with error bars. The only imprecision in the whole job comes from the tape measure, not the arithmetic.
The formula, with every term defined
cm = (ft × 12 + in) × 2.54back again: total inches = cm ÷ 2.54, then whole feet = floor(total inches ÷ 12) and the remaining inches = total inches − whole feet × 12
Where ft is whole feet, in is the remaining inches (0 to 11 — twelve inches would be another foot), and 2.54 is the exact number of centimetres in one inch. Centimetres are usually quoted to one decimal place (177.8 cm); a second decimal adds nothing a person can measure.
Worked examples, done step by step
Feet and inches to cm — 5 ft 10 in. Total inches: (5 × 12) + 10 = 70 in. Multiply by the exact factor: 70 × 2.54 = 177.80 cm. As metres, that is 1.7780 m.
Cm back to feet and inches — 180 cm. Total inches: 180 ÷ 2.54 = 70.87 in. Whole feet: 70.87 ÷ 12 = 5, with 10.87 in left over, which rounds to one decimal as 10.9 in. The answer is 5 ft 10.9 in — a touch over five-ten, which is why the rounded cm figure (180 cm) and the rounded ft/in figure (5′11″) can both be "right" while differing.
Common heights
| Feet & inches | Centimetres |
|---|---|
| 5′ 0″ | 152.40 |
| 5′ 2″ | 157.48 |
| 5′ 4″ | 162.56 |
| 5′ 6″ | 167.64 |
| 5′ 8″ | 172.72 |
| 5′ 10″ | 177.80 |
| 6′ 0″ | 182.88 |
| 6′ 2″ | 187.96 |
| 6′ 4″ | 193.04 |
Why the flip between the two systems matters
Official forms, visa and immigration paperwork, medical records and international clothing sizes ask for centimetres, while the US and UK talk in feet and inches. Each two-inch step in the table above is exactly 5.08 cm — a useful sanity check if a conversion ever looks off. The direction matters too: someone who says "I'm six foot" means exactly 6′0″, which is 182.88 cm, and the habit of rounding that to "about 183" is where visa forms and medical charts quietly disagree.
Reading the result, and its limits
The arithmetic is exact; the height is not. People are roughly a centimetre taller in the morning than the evening, as the spine compresses through the day, and a tape held at a slant — or shoes left on — adds more error than any rounding ever could. Measure barefoot, back straight against the wall, and treat the converted figure as carrying the same couple-of-centimetres uncertainty as the measurement it came from. This converter reports centimetres to two decimals so the exactness of the factor shows through; for a form, 177.8 cm is the number to write. For weight in both systems — the figure height is usually paired with — use the BMI calculator and the ideal weight calculator; for other measures, the unit converter covers length, weight, temperature and volume.
Frequently asked questions
How many cm is 5'10"?
Exactly 177.8 cm. Five feet ten inches is 70 inches in total — (5 × 12) + 10 — and 70 × 2.54 = 177.80 cm.
How do you convert feet and inches to cm?
Add the feet as inches (feet × 12), add the remaining inches, and multiply the total by 2.54. For 6 ft 2 in: (6 × 12) + 2 = 74 in, and 74 × 2.54 = 187.96 cm.
Is 2.54 cm per inch exact?
Yes — since the 1959 international agreement the inch is defined as exactly 2.54 cm, not measured as roughly that. One foot is exactly 30.48 cm for the same reason.
How do I convert cm back to feet and inches?
Divide by 2.54 to get total inches, take the whole feet from that, and keep the rest as inches. 180 cm ÷ 2.54 = 70.87 in, which is 5 ft 10.9 in.
