I produce about 80% of my families food by value, and about 50% by calories.
Based on what I have read that's not possible. The "usual" figure is that 1 person requires 1 acre, under optimal conditions. (Or 1 person requires 0.5 hectares).
If "family" = 3 people, and you are providing 50% of their calories, then you are feeding 1.5 people on that 1/4 acre. That would be 6 times more efficient than the "optimal" farm. Also, if it is possible to do this, it would require outside sources of water and fertilizer.
We mostly buy bulk cheap stuff like rice, soybeans, flour, and soybean oil, and get everything else from the backyard.
Then that is where you are getting most of your calories.