| Castleford to Popovo | 1,438.04 mi (2,314.30 km) |
| Castleford to Provadia | 1,492.01 mi (2,401.16 km) |
| Castleford to Radnevo | 1,473.76 mi (2,371.79 km) |
| Castleford to Radomir | 1,349.87 mi (2,172.40 km) |
| Castleford to Rakitovo | 1,418.87 mi (2,283.45 km) |
| Castleford to Rakovski | 1,437.58 mi (2,313.56 km) |
| Castleford to Razgrad | 1,441.03 mi (2,319.11 km) |
| Castleford to Razlog | 1,400.81 mi (2,254.39 km) |
| Castleford to Ruse | 1,406.57 mi (2,263.65 km) |
| Castleford to Samokov | 1,382.43 mi (2,224.81 km) |
| Castleford to Sandanski | 1,409.32 mi (2,268.08 km) |
| Castleford to Sevlievo | 1,409.38 mi (2,268.17 km) |
| Castleford to Shumen | 1,468.15 mi (2,362.76 km) |
| Castleford to Silistra | 1,445.20 mi (2,325.82 km) |
| Castleford to Sliven | 1,471.61 mi (2,368.32 km) |
