| Guyancourt Ban Tai | Indochina Time | -05:00 |
| Guyancourt Unterseen | Central European Time | 00:00 |
| Guyancourt Hoxie | Central Time | 07:00 |
| Guyancourt Youngsville | Central Time | 07:00 |
| Guyancourt Bamber Bridge | United Kingdom Time | 01:00 |
| Guyancourt Swillington | United Kingdom Time | 01:00 |
| Guyancourt Masai | Malaysia Time | -06:00 |
| Guyancourt Yountville | Pacific Time | 09:00 |
| Guyancourt Bensalem | Eastern Time | 06:00 |
| Guyancourt Unthank | United Kingdom Time | 01:00 |
| Guyancourt Howrah | India Standard Time | -03:30 |
| Guyancourt Ypres | Central European Time | 00:00 |
| Guyancourt Bennington | Eastern Time | 06:00 |
| Guyancourt Sweet Home | Pacific Time | 09:00 |
| Guyancourt Masai | Malaysia Time | -06:00 |
| Guyancourt Upland | Pacific Time | 09:00 |
| Guyancourt Bandar Baru Bangi | Malaysia Time | -06:00 |
| Guyancourt Swansboro | Eastern Time | 06:00 |
| Guyancourt Howell | Eastern Time | 06:00 |
| Guyancourt Upper Coomera | Eastern Australia Time | -08:00 |
| Guyancourt Balmain | Eastern Australia Time | -08:00 |
| Guyancourt Swanage | United Kingdom Time | 01:00 |
| Guyancourt Lauderdale-by-the-Sea | Eastern Time | 06:00 |
| Guyancourt Upper Darby | Eastern Time | 06:00 |
| Guyancourt Ballsbridge | Ireland Time | 01:00 |
| Guyancourt Swaffham | United Kingdom Time | 01:00 |
| Guyancourt Hubali-Dharwad | India Standard Time | -03:30 |
| Guyancourt Upper Ferntree Gully | Eastern Australia Time | -08:00 |
| Guyancourt Ballston Spa | Eastern Time | 06:00 |
| Guyancourt Swaffham Bulbeck | United Kingdom Time | 01:00 |
| Guyancourt Lauenburg | Central European Time | 00:00 |
| Guyancourt Uppala | India Standard Time | -03:30 |
| Guyancourt Ballydehob | Ireland Time | 01:00 |
| Guyancourt Swainsthorpe | United Kingdom Time | 01:00 |
| Guyancourt Hudson | Eastern Time | 06:00 |
| Guyancourt Tingalpa | Eastern Australia Time | -08:00 |
| Guyancourt Ballarat Central | Eastern Australia Time | -08:00 |
| Guyancourt Syracuse | Central European Time | 00:00 |
| Guyancourt Lauerz | Central European Time | 00:00 |
| Guyancourt Tinajo | Western European Time | 01:00 |
| Guyancourt Ballina | Eastern Australia Time | -08:00 |
| Guyancourt Sylvester | Eastern Time | 06:00 |
| Guyancourt Itabashi | Japan Time | -07:00 |
| Guyancourt Tintagel | United Kingdom Time | 01:00 |
| Guyancourt Balwyn | Eastern Australia Time | -08:00 |
| Guyancourt Sylvan Lake | Mountain Time | 08:00 |
| Guyancourt Laudio | Central European Time | 00:00 |
| Guyancourt Tillsonburg | Eastern Time | 06:00 |
| Guyancourt Balsièges | Central European Time | 00:00 |
| Guyancourt Sydney | Eastern Australia Time | -08:00 |