Calories in homemade water kefir?

Does anybody know how to get an accurate calorie count of homemade water kefir?

My first step of the fermentation is 4 cups of spring water and 1/4 cup raw sugar. 2 or 3 days later I strain the grains and do a second fermentation by adding a bit of grape juice.

My milk kefir I just use the calories from the milk (even though I guess it technically changes), but confused what to do with the water since theoretically the sugar should be mostly gone.