| 644 cm * | 0.032808399 ft | = 21.1286089239 ft | 
| 1 cm | 
| Natuurkundige eenheid | Lengte | 
|---|---|
| Nanometer | 6440000000.0 nm | 
| Micrometer | 6440000.0 µm | 
| Millimeter | 6440.0 mm | 
| Centimeter | 644.0 cm | 
| Inch | 253.543307087 in | 
| Voet | 21.1286089239 ft | 
| Yard | 7.0428696413 yd | 
| Meter | 6.44 m | 
| Kilometer | 0.00644 km | 
| Mijl | 0.0040016305 mi | 
| Zeemijl | 0.0034773218 nmi | 
