How big is the S7 battery actually? Android OS Battery stats make no sense

I've been getting horrible battery life and have some bad wakelocks from System, OS and Play Services....but my question here what does the OS see as the battery size? I thought the S7 had a 3000 mAh battery. But when I look at my battery stats, I see 456 mAh calculated for Android System. If that has used up 25% of my consumed battery, that suggests that the OS thinks I've used 1824 mAh. And for the OS thinks I've got 13% remaining after using 1824 mAh, the OS must think I have a battery that's only 2096 mAh in capacity. When I do the same calculation for the other listed battery users, I keep getting a number roughly equivalent to 2100-2200 mAh capacity. So is it a 2100 mAh battery, or 3000 mAh?

See here for screenshots - that's with only 1hr 23min SOT. This is a Verizon S7 (not Edge), so it's SD820.