Many game jams you can't separete time for personal needs from game dev, so if you consider Ludum Dare that have 48h, if you subtract 8h of sleep for each day and 3h for others needs you get around 26h (or only 10h if you have a 8h work in the days of the jams) in total for making the game. In 9 days would be almost 3h/day.
But anyway, hope you have enough time to make your game, even if you end up not using the full 48h ^^