Length Converter Calculator
Length Unit Quick Reference
The two most commonly used measurement systems for human height and growth are the metric system (SI) and the imperial/US customary system. Understanding how the units relate to each other — and where each system is used — is the starting point for any conversion.
Exact Conversion Factors
All conversions below use the internationally agreed exact definitions established by the International Bureau of Weights and Measures (BIPM). The inch was redefined as exactly 2.54 cm in 1959 — all imperial-to-metric conversions derive from this single relationship.
| From | To cm | To m | To inches | To feet |
|---|---|---|---|---|
| 1 millimeter (mm) | 0.1 | 0.001 | 0.03937 | 0.003281 |
| 1 centimeter (cm) | 1 | 0.01 | 0.39370 | 0.032808 |
| 1 meter (m) | 100 | 1 | 39.3701 | 3.28084 |
| 1 kilometer (km) | 100,000 | 1,000 | 39,370.1 | 3,280.84 |
| 1 inch (in) | 2.54 | 0.0254 | 1 | 0.08333 |
| 1 foot (ft) | 30.48 | 0.3048 | 12 | 1 |
| 1 yard (yd) | 91.44 | 0.9144 | 36 | 3 |
| 1 mile (mi) | 160,934 | 1,609.34 | 63,360 | 5,280 |
Common Height Conversions
For growth and height tracking, the most frequently needed conversions are between centimeters and feet-and-inches. The table below covers the range of typical human heights.
| cm | ft & in | inches only | meters |
|---|---|---|---|
| 145 cm | 4 ft 9 in | 57.1 in | 1.45 m |
| 150 cm | 4 ft 11 in | 59.1 in | 1.50 m |
| 155 cm | 5 ft 1 in | 61.0 in | 1.55 m |
| 160 cm | 5 ft 3 in | 63.0 in | 1.60 m |
| 163 cm | 5 ft 4 in | 64.2 in | 1.63 m |
| 165 cm | 5 ft 5 in | 65.0 in | 1.65 m |
| 168 cm | 5 ft 6 in | 66.1 in | 1.68 m |
| 170 cm | 5 ft 7 in | 66.9 in | 1.70 m |
| 173 cm | 5 ft 8 in | 68.1 in | 1.73 m |
| 175 cm | 5 ft 9 in | 68.9 in | 1.75 m |
| 178 cm | 5 ft 10 in | 70.1 in | 1.78 m |
| 180 cm | 5 ft 11 in | 70.9 in | 1.80 m |
| 183 cm | 6 ft 0 in | 72.0 in | 1.83 m |
| 185 cm | 6 ft 1 in | 72.8 in | 1.85 m |
| 188 cm | 6 ft 2 in | 74.0 in | 1.88 m |
| 190 cm | 6 ft 3 in | 74.8 in | 1.90 m |
| 193 cm | 6 ft 4 in | 76.0 in | 1.93 m |
Why feet-and-inches is more complex than it looks. Unlike purely decimal systems, feet-and-inches requires two separate values with a base-12 relationship between them. 5 ft 11.5 in is not "5.11 feet" — it is 5 + 11.5/12 = 5.958 feet. This is the most common source of conversion errors. Always convert to total inches first, then extract the foot and inch components separately.
Frequently Asked Questions
How do I convert cm to feet and inches?
Divide centimeters by 2.54 to get total inches. Then divide total inches by 12 and take the whole number for feet — the remainder is the inches. For example, 170 cm divided by 2.54 equals 66.93 inches. Dividing 66.93 by 12 gives 5 feet with a remainder of 6.93 inches — so 170 cm equals 5 feet 6.9 inches, typically rounded to 5 feet 7 inches. The calculator does this automatically and displays the exact breakdown.
How do I convert feet and inches to cm?
First convert all feet to inches by multiplying by 12, then add any remaining inches. Then multiply the total inches by 2.54. For example, 5 feet 8 inches equals (5 × 12) + 8 = 68 total inches. Multiplying 68 by 2.54 gives 172.72 cm. To use this calculator for feet-and-inches input, select feet as the from-unit and enter the decimal equivalent — 5 feet 8 inches is entered as 5.667 feet (68 ÷ 12).
What is the exact value of 6 feet in cm?
Exactly 182.88 cm. This is derived from the exact definition: 1 foot = 30.48 cm (since 1 inch = 2.54 cm exactly, and 1 foot = 12 inches). So 6 feet = 6 × 30.48 = 182.88 cm. This is an exact value with no rounding — 182.88 cm is precisely 6 feet. In practice, heights are often rounded to 183 cm in clinical and everyday contexts.
Why does the US use inches and feet instead of metric?
The United States is one of only three countries — alongside Liberia and Myanmar — that has not officially adopted the metric system as the primary unit system. The US retained the customary system inherited from British imperial usage after independence, and multiple attempts at metrication in the 20th century were not mandated. For scientific, medical, and most technical work in the US, metric is standard — but for everyday personal measurements including height, the imperial system remains dominant in American culture.
How precise are the conversions in this calculator?
All conversions use the exact SI-defined factor of 1 inch = 2.54 cm, from which all other imperial-to-metric relationships derive. The calculator maintains full floating-point precision internally and displays up to 4 significant decimal places depending on the unit. For human height purposes, differences below 0.1 cm or 0.05 inches are clinically and practically negligible — the limiting factor is always the precision of the original measurement, not the conversion math.
