Question: is all of france in one time zone

Answer: Yes, Metropolitan France uses Central European Time (heure d'Europe centrale, HEC: UTC+01:00) and Central European Summer Time (heure d'été d'Europe centrale: UTC+02:00). Daylight saving time is observed in Metropolitan France from the last Sunday in March (02:00 CET) to the last Sunday in October (03:00 CEST). With its overseas territories, France uses 12 different time zones, more than any other country in the world.