Height is a two-part number
Most unit conversions produce a single decimal. Height does not: outside the metric world it is written as feet and inches, so 175 cm has to become 5 feet 8.9 inches rather than 5.74 feet. That second step — splitting the decimal remainder into inches — is where the arithmetic usually goes wrong, so it is done here explicitly.
Rounding, and why passports disagree with each other
Nobody quotes their height to a tenth of an inch, so the figure gets rounded — and a rounded height is ambiguous by up to half an inch in either direction. Someone who says they are 5′10″ may be anywhere from 177.2 cm to 178.4 cm. This is why a height written on one form in centimetres and another in inches can look inconsistent when both are correct.
The tool gives you both: the exact conversion to a tenth of an inch, and the conventional rounded figure.
Common heights worth memorising
Five feet is 152.4 cm. Five foot six is 167.6 cm. Five foot ten is 177.8 cm. Six feet is 182.9 cm, and six foot three is 190.5 cm — which is exactly 75 inches, one of the few round crossovers between the systems.
Measure at the right time of day
Human height varies by roughly 1–2 cm over a day as spinal discs compress, so a morning measurement is genuinely taller than an evening one. If you are converting a height for a medical form or a record where consistency matters, note when it was taken — the daily variation is larger than the rounding error in the conversion itself.