| Serpa to Popovo | 1,799.52 mi (2,896.04 km) |
| Serpa to Provadia | 1,859.94 mi (2,993.28 km) |
| Serpa to Radnevo | 1,785.13 mi (2,872.90 km) |
| Serpa to Radomir | 1,632.88 mi (2,627.86 km) |
| Serpa to Rakitovo | 1,690.91 mi (2,721.25 km) |
| Serpa to Rakovski | 1,735.70 mi (2,793.34 km) |
| Serpa to Razgrad | 1,813.83 mi (2,919.07 km) |
| Serpa to Razlog | 1,659.35 mi (2,670.46 km) |
| Serpa to Ruse | 1,786.06 mi (2,874.38 km) |
| Serpa to Samokov | 1,663.63 mi (2,677.35 km) |
| Serpa to Sandanski | 1,650.32 mi (2,655.93 km) |
| Serpa to Sevlievo | 1,742.95 mi (2,805.00 km) |
| Serpa to Shumen | 1,834.70 mi (2,952.67 km) |
| Serpa to Silistra | 1,851.49 mi (2,979.68 km) |
| Serpa to Sliven | 1,804.88 mi (2,904.67 km) |
