| Harpenden to Nyon | 478.90 mi (770.71 km) |
| Harpenden to Oberriet | 541.73 mi (871.82 km) |
| Harpenden to Obersiggenthal | 488.39 mi (785.99 km) |
| Harpenden to Oberwil | 461.57 mi (742.83 km) |
| Harpenden to Oberwingert | 504.05 mi (811.19 km) |
| Harpenden to Oftringen | 483.23 mi (777.68 km) |
| Harpenden to Olten | 481.09 mi (774.23 km) |
| Harpenden to Onex | 486.51 mi (782.96 km) |
| Harpenden to Opfikon | 500.53 mi (805.52 km) |
| Harpenden to Ostermundigen | 486.60 mi (783.10 km) |
| Harpenden to Payerne | 476.06 mi (766.15 km) |
| Harpenden to Pfaffikon | 511.22 mi (822.74 km) |
| Harpenden to Plan-les-Ouates | 487.91 mi (785.21 km) |
| Harpenden to Pratteln | 466.40 mi (750.60 km) |
| Harpenden to Prilly | 481.14 mi (774.32 km) |
