Saint-Thomas-de-Conac is a commune in the canton of Mirambeau in the Charente-Maritime department in the Poitou-Charentes region in western France.
| Year | Population | Density | Percent of the canton |
|---|---|---|---|
| 1962 | 699 | - | - |
| 1968 | 778 | - | - |
| 1975 | 723 | - | - |
| 1982 | 657 | - | - |
| 1990 | 610 | - | - |
| 1999 | 545 | 19 /km² | 75.51% |