If you want to know for sure, send it to a lab. I'd be happy to provide a link.
I'm assuming you want to know the amount of residual sugar, not any type of caloric content total. Please correct me if I'm wrong.
And all I did was calculate (I did it in my head so it was just an estimate) of how much maltose it would take to reach that Specfic Gravity (Your actual ending gravity) in a 5 gallon batch.