| Kalkar to Oestrich-Winkel | 141.34 mi (227.46 km) |
| Kalkar to Offenburg | 237.48 mi (382.18 km) |
| Kalkar to Oftersheim | 192.07 mi (309.11 km) |
| Kalkar to Ohrdruf | 201.91 mi (324.94 km) |
| Kalkar to Ohringen | 225.05 mi (362.19 km) |
| Kalkar to Olbernhau | 313.54 mi (504.60 km) |
| Kalkar to Olching | 330.97 mi (532.64 km) |
| Kalkar to Oldenburg | 126.37 mi (203.38 km) |
| Kalkar to Oldenburg in Holstein | 260.13 mi (418.64 km) |
| Kalkar to Olfen | 46.71 mi (75.17 km) |
| Kalkar to Olpe | 83.10 mi (133.73 km) |
| Kalkar to Olsberg | 97.89 mi (157.54 km) |
| Kalkar to Oranienburg | 301.90 mi (485.86 km) |
| Kalkar to Ortenberg | 153.39 mi (246.86 km) |
| Kalkar to Oschatz | 294.44 mi (473.85 km) |
