| Irthlingborough to Popovo | 1,380.00 mi (2,220.89 km) |
| Irthlingborough to Provadia | 1,435.62 mi (2,310.40 km) |
| Irthlingborough to Radnevo | 1,411.88 mi (2,272.20 km) |
| Irthlingborough to Radomir | 1,283.01 mi (2,064.80 km) |
| Irthlingborough to Rakitovo | 1,352.55 mi (2,176.72 km) |
| Irthlingborough to Rakovski | 1,373.84 mi (2,210.99 km) |
| Irthlingborough to Razgrad | 1,384.11 mi (2,227.52 km) |
| Irthlingborough to Razlog | 1,333.01 mi (2,145.28 km) |
| Irthlingborough to Ruse | 1,349.59 mi (2,171.96 km) |
| Irthlingborough to Samokov | 1,316.12 mi (2,118.09 km) |
| Irthlingborough to Sandanski | 1,340.28 mi (2,156.97 km) |
| Irthlingborough to Sevlievo | 1,348.19 mi (2,169.71 km) |
| Irthlingborough to Shumen | 1,411.18 mi (2,271.07 km) |
| Irthlingborough to Silistra | 1,391.61 mi (2,239.58 km) |
| Irthlingborough to Sliven | 1,411.63 mi (2,271.80 km) |
