| Project Name | KEK Sei Mangkei |
| Developer Name | PT. Perkebunan Nusantara III (PTPN III) |
| Year of Completion | 2012 |
| Total Landbank (Ha) | N/A |
| Primary Industry | Palm oil and rubber |
| Website | kek.go.id/kawasan/Sei-Mangkei |
| City | Simalungun |
| Province | North Sumatera |
| Population | 1,067,499 in (2025) |
| People Density | 231.99/km2 |
| Regional Minimum Wage (UMR) | IDR 3,351,403 in (2026) |