Length Converter
Convert mm, cm, m, km, in, ft, yd, mi and nautical miles instantly.
Inputs
mm
cm
m
km
in
ft
yd
mi
nmi
About Length Units
- The meter (m) is the SI base unit of length. Since 2019 it has been defined as the distance light travels in vacuum in exactly 1/299,792,458 of a second. All metric units — millimeter (mm), centimeter (cm) and kilometer (km) — are simply powers of ten of the meter.
- Imperial and US customary length units such as the inch, foot, yard and mile have roots in historical body measurements. Since 1959 the international inch has been fixed at exactly 25.4 mm, which anchors all imperial-to-metric conversions: 1 ft = 304.8 mm, 1 yd = 914.4 mm, 1 mi = 1,609,344 mm.
- The nautical mile (nmi) is derived from the Earth''s geometry: 1 nmi equals one arcminute of latitude along a meridian, standardised at exactly 1,852 m. It is the universal unit of distance in aviation and maritime navigation, and 1 knot = 1 nmi/h.
- Practical quick-reference: 1 ft = 12 in · 1 yd = 3 ft · 1 mi = 1,760 yd = 5,280 ft. In metric: 1 km = 1,000 m = 100,000 cm = 1,000,000 mm. For everyday use, 1 inch ≈ 2.54 cm and 1 metre ≈ 3.281 ft.
| 1 单位 | = 米 (m) | = 英寸 (in) | = 英尺 (ft) |
|---|---|---|---|
| 毫米(mm) | 0.001 | 0.03937 | 0.003281 |
| 厘米(cm) | 0.01 | 0.3937 | 0.03281 |
| 米(m) | 1 | 39.3701 | 3.28084 |
| 千米(km) | 1000 | 39,370.1 | 3,280.84 |
| 英寸(in) | 0.0254 | 1 | 0.08333 |
| 英尺(ft) | 0.3048 | 12 | 1 |
| 码(yd) | 0.9144 | 36 | 3 |
| 英里(mi) | 1,609.344 | 63,360 | 5,280 |
| 海里(nmi) | 1,852 | 72,913.4 | 6,076.12 |