| 21 cm * | 0.032808399 ft | = 0.688976378 ft | 
| 1 cm | 
| Unidad de medida | Longitudes | 
|---|---|
| Nanómetro | 210000000.0 nm | 
| Micrómetro | 210000.0 µm | 
| Milímetro | 210.0 mm | 
| Centímetro | 21.0 cm | 
| Pulgada | 8.2677165354 in | 
| Pie | 0.688976378 ft | 
| Yarda | 0.2296587927 yd | 
| Metro | 0.21 m | 
| Kilómetro | 0.00021 km | 
| Milla | 0.000130488 mi | 
| Milla náutica | 0.0001133909 nmi | 
