America’s bloodiest day:
| Killed: | Union 2,000 | Confederate 1,550 | Total Killed: 3,650 |
| Wounded: | Union 9,550 | Confederate 7,750 | Total Wounded: 17,300 |
| Missing/Captured: | Union 750 | Confederate 1,020 | Total Missing: 1,770 |
| Total: | Union 12,400 | Confederate 10,320 | Total Casualties: 22,720 |
As a rule of thumb, about 20% of the wounded died of their wounds and 30% of the missing had been killed (in the days before dog-tags to identify the dead). Accordingly, an estimate of the total dead from the one-day battle: 7,640.
Source: National Park Service