| 21 ft * | 0.3048 m | = 6.4008 m |
| 1 ft |
| Eenhede van meting | Lengte |
|---|---|
| Nanometer | 6400800000.0 nm |
| Mikrometer | 6400800.0 µm |
| Millimeter | 6400.8 mm |
| Sentimeter | 640.08 cm |
| Duim | 252.0 in |
| Voet | 21.0 ft |
| Jaart | 7.0 yd |
| Meter | 6.4008 m |
| Kilometer | 0.0064008 km |
| Myl | 0.0039772727 mi |
| Seemyl | 0.0034561555 nmi |