| Guyancourt Detroit | Eastern Time | 06:00 |
| Guyancourt Matola | Central Africa Time | 00:00 |
| Guyancourt Culiacán Rosales | Mexican Pacific Time | 08:00 |
| Guyancourt Zaragoza | Central European Time | 00:00 |
| Guyancourt Gorakhpur | India Standard Time | -03:30 |
| Guyancourt Xiangtan | China Time | -06:00 |
| Guyancourt Ipoh | Malaysia Time | -06:00 |
| Guyancourt Mississauga | Eastern Time | 06:00 |
| Guyancourt Boston | Eastern Time | 06:00 |
| Guyancourt Puyang Chengguanzhen | China Time | -06:00 |
| Guyancourt Nantong | China Time | -06:00 |
| Guyancourt Mudanjiang | China Time | -06:00 |
| Guyancourt Athens | Eastern European Time | -01:00 |
| Guyancourt Santo André | Brasilia Time | 05:00 |
| Guyancourt Nouakchott | Greenwich Mean Time | 02:00 |
| Guyancourt Pointe-Noire | West Africa Time | 01:00 |
| Guyancourt Aguascalientes | Central Time | 07:00 |
| Guyancourt Memphis | Central Time | 07:00 |
| Guyancourt Kryvyi Rih | Eastern European Time | -01:00 |
| Guyancourt Acapulco | Central Time | 07:00 |
| Guyancourt João Pessoa | Brasilia Time | 05:00 |
| Guyancourt Ansan-si | Korean Time | -07:00 |
| Guyancourt Benghazi | Eastern European Time | 00:00 |
| Guyancourt Frankfurt | Central European Time | 00:00 |
| Guyancourt Krasnodar | Moscow Time | -01:00 |
| Guyancourt Guilin | China Time | -06:00 |
| Guyancourt Palermo | Central European Time | 00:00 |
| Guyancourt Colombo | India Standard Time | -03:30 |
| Guyancourt Lilongwe | Central Africa Time | 00:00 |
| Guyancourt Oran | Central European Time | 01:00 |
| Guyancourt Diyarbakir | Turkey Time | -01:00 |
| Guyancourt Taguig | Philippine Time | -06:00 |
| Guyancourt New South Memphis | Central Time | 07:00 |
| Guyancourt Ulyanovsk | Ulyanovsk Time | -02:00 |
| Guyancourt Kotli | Pakistan Time | -03:00 |
| Guyancourt Okayama | Japan Time | -07:00 |
| Guyancourt Zhanjiang | China Time | -04:00 |
| Guyancourt Ahmadi | Arabian Time | -01:00 |
| Guyancourt Yogyakarta | Western Indonesia Time | -05:00 |
| Guyancourt North York | Eastern Time | 06:00 |
| Guyancourt Chișinău | Eastern European Time | -01:00 |
| Guyancourt Wrocław | Central European Time | 00:00 |
| Guyancourt Cheongju-si | Korean Time | -07:00 |
| Guyancourt Anyang-si | Korean Time | -07:00 |
| Guyancourt Tebessa | Central European Time | 01:00 |
| Guyancourt Zhenjiang | China Time | -06:00 |
| Guyancourt Portland | Pacific Time | 09:00 |
| Guyancourt Winnipeg | Central Time | 07:00 |
| Guyancourt Andong | China Time | -06:00 |
| Guyancourt Oklahoma City | Central Time | 07:00 |