| Port Glasgow to Popovo | 1,613.57 mi (2,596.79 km) |
| Port Glasgow to Provadia | 1,665.41 mi (2,680.22 km) |
| Port Glasgow to Radnevo | 1,653.44 mi (2,660.95 km) |
| Port Glasgow to Radomir | 1,535.17 mi (2,470.62 km) |
| Port Glasgow to Rakitovo | 1,603.41 mi (2,580.43 km) |
| Port Glasgow to Rakovski | 1,619.37 mi (2,606.13 km) |
| Port Glasgow to Razgrad | 1,615.26 mi (2,599.51 km) |
| Port Glasgow to Razlog | 1,586.89 mi (2,553.85 km) |
| Port Glasgow to Ruse | 1,581.03 mi (2,544.42 km) |
| Port Glasgow to Samokov | 1,567.07 mi (2,521.96 km) |
| Port Glasgow to Sandanski | 1,596.58 mi (2,569.45 km) |
| Port Glasgow to Sevlievo | 1,588.53 mi (2,556.50 km) |
| Port Glasgow to Shumen | 1,642.33 mi (2,643.08 km) |
| Port Glasgow to Silistra | 1,615.50 mi (2,599.90 km) |
| Port Glasgow to Sliven | 1,649.18 mi (2,654.10 km) |
