| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Derry | 1 | 33,944 | 34,080 | -0.14% | 957 | 35 | Town |
| Salem | 2 | 32,114 | 30,284 | 0.77% | 1,293 | 25 | Town |
| Londonderry | 3 | 28,610 | 26,104 | 2.75% | 681 | 42 | Town |
| Portsmouth | 4 | 23,164 | 21,990 | 0.59% | 1,479 | 16 | City |
| Windham | 5 | 16,351 | 15,836 | 0.57% | 611 | 27 | Town |
| Hampton | 6 | 16,343 | 16,233 | -0.23% | 1,266 | 13 | Town |
| Exeter | 7 | 16,201 | 16,067 | -0.07% | 826 | 20 | Town |
| Raymond | 8 | 11,077 | 10,705 | 0.24% | 384 | 29 | Town |
| Newmarket | 9 | 9,776 | 9,423 | 1.34% | 776 | 13 | Town |
| Hampstead | 10 | 9,105 | 8,998 | -0.05% | 678 | 13 | Town |
| Seabrook | 11 | 8,424 | 8,403 | -0.07% | 938 | 9 | Town |
| Epping | 12 | 8,163 | 7,153 | 2.38% | 314 | 26 | Town |
| Plaistow | 13 | 7,850 | 7,834 | 0.03% | 741 | 11 | Town |
| Stratham | 14 | 7,728 | 7,688 | -0.09% | 510 | 15 | Town |
| Atkinson | 15 | 7,451 | 7,100 | 0.73% | 668 | 11 | Town |
| Sandown | 16 | 6,792 | 6,567 | 0.58% | 487 | 14 | Town |
| Auburn | 17 | 6,425 | 5,972 | 1.4% | 253 | 25 | Town |
| Kingston | 18 | 6,278 | 6,192 | -0.16% | 317 | 20 | Town |
| Rye | 19 | 5,727 | 5,534 | 0.67% | 453 | 13 | Town |
| Nottingham | 20 | 5,523 | 5,243 | 0.6% | 119 | 46 | Town |
| Chester | 21 | 5,343 | 5,226 | 0.39% | 205 | 26 | Town |
| Brentwood | 22 | 5,071 | 4,492 | 3.01% | 302 | 17 | Town |
| Deerfield | 23 | 5,007 | 4,856 | 0.36% | 99 | 51 | Town |
| Fremont | 24 | 4,959 | 4,742 | 0.73% | 289 | 17 | Town |
| Newton | 25 | 4,857 | 4,824 | 0.12% | 495 | 10 | Town |
| Northwood | 26 | 4,813 | 4,642 | 1.18% | 171 | 28 | Town |
| Danville | 27 | 4,672 | 4,418 | 0.47% | 401 | 12 | Town |
| North Hampton | 28 | 4,518 | 4,539 | -0.18% | 325 | 14 | Town |
| Candia | 29 | 4,287 | 4,017 | 0.92% | 141 | 30 | Town |
| Greenland | 30 | 4,165 | 4,066 | 0.53% | 397 | 10 | Town |
| East Kingston | 31 | 2,435 | 2,438 | 0.04% | 246 | 10 | Town |
| Hampton Falls | 32 | 2,370 | 2,401 | -0.38% | 194 | 12 | Town |
| Kensington | 33 | 2,094 | 2,091 | 0.1% | 175 | 12 | Town |
| Newfields | 34 | 1,772 | 1,775 | -0.17% | 250 | 7 | Town |
| New Castle | 35 | 996 | 994 | -0.1% | 1,231 | 1 | Town |
| South Hampton | 36 | 892 | 890 | 0% | 111 | 8 | Town |
Derry is the largest city in Rockingham County, with a population of 33,944.
South Hampton is the smallest city in Rockingham County, with a population of 892.
There are 36 cities in Rockingham County, New Hampshire.