| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Iowa Falls | 1 | 4,989 | 5,092 | -0.48% | 881 | 6 | City |
| Eldora | 2 | 2,579 | 2,656 | -0.54% | 602 | 4 | City |
| Ackley | 3 | 1,516 | 1,591 | -0.92% | 617 | 2 | City |
| Hubbard | 4 | 829 | 858 | -0.72% | 467 | 2 | City |
| Alden | 5 | 729 | 761 | -0.82% | 473 | 2 | City |
| Radcliffe | 6 | 536 | 556 | -0.74% | 538 | 1 | City |
| Union | 7 | 379 | 394 | -0.79% | 664 | 1 | City |
| McCallsburg | 8 | 354 | 350 | 0.28% | 776 | 0 | City |
| Steamboat Rock | 9 | 259 | 265 | -0.38% | 480 | 1 | City |
| New Providence | 10 | 227 | 235 | -0.87% | 227 | 1 | City |
| Whitten | 11 | 96 | 100 | -1.03% | 193 | 0 | City |
| Buckeye | 12 | 81 | 83 | -1.22% | 82 | 1 | City |
Iowa Falls is the largest city in Hardin County, with a population of 4,989.
Buckeye is the smallest city in Hardin County, with a population of 81.
There are 12 cities in Hardin County, Iowa.