Millimeters to miles to parsecs - every factor exact, from the same legally defined relationships (inch = 25.4 mm precisely) that standards bodies use.
| From | Equals |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot | 0.3048 m |
| 1 yard | 0.9144 m |
| 1 mile | 1.609344 km |
| 1 kilometre | 0.6213711922 mi |
| 1 metre | 3.280839895 ft |
| 1 centimetre | 0.3937007874 in |
| 1 nautical mile | 1.852 km |
Every value in this table is computed by the same conversion engine as the tool above - not typed in by hand - so the tool and the table can never disagree.
Since the 1959 International Yard and Pound Agreement, the inch has been legally defined as exactly 25.4 millimeters - not measured, defined. Everything imperial follows from it: the foot (12 inches = 0.3048 m exactly), the yard (0.9144 m), and the mile (1,609.344 m). That's why this converter's factors carry no rounding error - the relationships are fixed by international treaty, and the engine behind this page has been verified against NIST Special Publication 811, the US government's own conversion factor reference.
Beyond the everyday ones, this converter covers the surveyor's chain (66 ft) and furlong (660 ft) - which is why an acre is exactly one chain by one furlong - the nautical mile (1,852 m exactly, the basis of the knot), and the astronomical set: the astronomical unit (Earth-Sun distance, fixed by the IAU in 2012 at exactly 149,597,870,700 m), the light-year, and the parsec. Same engine, same exactness, from millimeters to parsecs.