I would normally say a minor game (5C,5D) needs 29 points (or a good 28) to have a good chance of making. Of course subject to suit lengths, and how well the hands fit etc. Probably best to use the losing trick count. With 25-27/28 points and a minor fit I'd normally want to take a chance at 3NT instead of a minor game, and hope that the opposition cannot take 5 tricks from the start (or just fail to realise they can).

Having said that, sometimes if one bends the rules one can bid and make a small slam on just 27 points, like on Saturday. The rules need to be bent to fit the hands in question at times.