One point usually "averages" about 50- 60 calories, but the range can be from about 30 - 90, so it really depends on how much fat and fiber you are eating.
40 - 45 points probably would be about right, but if you have to be more precise than that, you could try tracking both for a few days to find your average based on the types of food you eat.
But remember this can be up or down based on fat and fiber and DOES NOT include the 200-250 calories a day that W/W built into the program for free veggies