| Houghton Regis to Sinop | 1,793.07 mi (2,885.66 km) |
| Houghton Regis to Siran | 2,035.16 mi (3,275.28 km) |
| Houghton Regis to Sirnak | 2,290.13 mi (3,685.61 km) |
| Houghton Regis to Sirvan | 2,248.10 mi (3,617.96 km) |
| Houghton Regis to Sivas | 1,964.72 mi (3,161.91 km) |
| Houghton Regis to Sivasli | 1,719.82 mi (2,767.79 km) |
| Houghton Regis to Siverek | 2,147.97 mi (3,456.82 km) |
| Houghton Regis to Sivrice | 2,117.08 mi (3,407.10 km) |
| Houghton Regis to Sivrihisar | 1,750.67 mi (2,817.42 km) |
| Houghton Regis to Sogut | 1,670.17 mi (2,687.88 km) |
| Houghton Regis to Sogutlu | 1,644.31 mi (2,646.26 km) |
| Houghton Regis to Soke | 1,665.45 mi (2,680.28 km) |
| Houghton Regis to Solhan | 2,167.94 mi (3,488.96 km) |
| Houghton Regis to Soma | 1,604.58 mi (2,582.32 km) |
| Houghton Regis to Sorgun | 1,885.60 mi (3,034.58 km) |
