14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Carmel town | 1 | 33,875 | 33,606 | -0.01% | 944 | 35.89 | Town |
| Southeast town | 2 | 18,243 | 18,038 | 0.12% | 575 | 31.72 | Town |
| Putnam Valley town | 3 | 11,560 | 11,741 | -0.7% | 281 | 41.11 | Town |
| Patterson town | 4 | 11,449 | 11,529 | -0.46% | 355 | 32.21 | Town |
| Philipstown town | 5 | 9,763 | 9,822 | -0.5% | 200 | 48.80 | Town |
| Carmel | 6 | 9,075 | 6,841 | 7.14% | 983 | 9.23 | CDP |
| Mahopac | 7 | 8,875 | 8,914 | 0.37% | 1,448 | 6.13 | CDP |
| Putnam Lake | 8 | 3,822 | 3,943 | -0.03% | 839 | 4.55 | CDP |
| Brewster Hill | 9 | 2,688 | 2,574 | 1.51% | 3,090 | 0.87 | CDP |
| Brewster | 10 | 2,495 | 2,507 | -0.08% | 5,081 | 0.49 | Village |
| Cold Spring | 11 | 1,997 | 1,987 | 0.1% | 3,362 | 0.59 | Village |
| Brewster Heights | 12 | 1,578 | 1,067 | 7.2% | 2,994 | 0.53 | CDP |
| Peach Lake | 13 | 1,279 | 1,932 | -1.77% | 555 | 2.30 | CDP |
| Nelsonville | 14 | 636 | 621 | 0.47% | 615 | 1.03 | Village |
Carmel town is the largest city in Putnam County, with a population of 33,875.
Nelsonville is the smallest city in Putnam County.
There are 14 cities in Putnam County, New York.