Massachusetts counties by area
Official, comparable measurements for 14 counties and county equivalents.
- 46.2–103.2 mi²
- 394.2–492.5 mi²
- 527.2–617 mi²
- 658.5–817.9 mi²
- 926.9–1,510.7 mi²
- 101–206 per mi²
- 311–588 per mi²
- 592–830 per mi²
- 1,073–1,868 per mi²
- 2,042–13,593 per mi²
Understanding Massachusetts’s county areas
The land-area range runs from Nantucket County at 46.2 mi² to Worcester County at 1,510.7 mi². The largest has 32.7 times the land area of the smallest and accounts for 19.4% of the combined county land in Massachusetts. Compare with every state’s largest county.
The median county-equivalent land area is 540.2 mi², below the national median of 604.5 mi². The median describes the middle of the county size distribution; it does not describe how people or development are distributed. A state with a few very large counties can have a much smaller median than its largest entry suggests.
Where water changes the picture
Barnstable County has the most assigned water area, at 911.4 mi². Nantucket County has the highest water share, with water making up 84.8% of its total area. Water area and water percentage answer different questions: the first measures an amount, while the second measures the mix of land and water.
Across all 14 entries, water accounts for 26.1% of the combined total area. This is calculated from the summed land and water measurements, rather than averaging county percentages, which would give each small and large county equal weight.
Where people live
An estimated 7,154,084 people lived in Massachusetts on July 1, 2025 (+1.7% since 2020), or 2.1% of the national total in this dataset. Middlesex County is the most populous county equivalent, with 1,669,979 residents — 23.3% of the state. The largest by land, Worcester County, has 888,502.
Across the state there are 917 people per square mile of land. County densities range from 13,593 in Suffolk County to 101 in Franklin County; the median county equivalent has 673. Switch the map above to density to see where the state’s population concentrates.
Compare the largest and smallest county equivalents in Massachusetts to see land, water, and total area on the same scale.
These calculations use the 2026 Census county records listed below. County-equivalent boundaries vary between states; area alone does not measure population, density, or usable land. See coverage and calculation rules.
Complete area table
Sorted from largest to smallest land area.
| # | County / equivalent | Land | Water | Water share | Population | Per mi² |
|---|---|---|---|---|---|---|
| 1 | Worcester CountyGEOID 25027 | 1,510.7 mi² | 68.5 mi² | 4.3% | 888,502 | 588 |
| 2 | Berkshire CountyGEOID 25003 | 926.9 mi² | 19.6 mi² | 2.1% | 128,224 | 138 |
| 3 | Middlesex CountyGEOID 25017 | 817.9 mi² | 29 mi² | 3.4% | 1,669,979 | 2,042 |
| 4 | Franklin CountyGEOID 25011 | 699.2 mi² | 25.3 mi² | 3.5% | 70,698 | 101 |
| 5 | Plymouth CountyGEOID 25023 | 658.5 mi² | 434.8 mi² | 39.8% | 546,829 | 830 |
| 6 | Hampden CountyGEOID 25013 | 617 mi² | 17.1 mi² | 2.7% | 464,338 | 753 |
| 7 | Bristol CountyGEOID 25005 | 553.1 mi² | 138 mi² | 20% | 593,640 | 1,073 |
| 8 | Hampshire CountyGEOID 25015 | 527.2 mi² | 18 mi² | 3.3% | 164,065 | 311 |
| 9 | Essex CountyGEOID 25009 | 492.5 mi² | 336 mi² | 40.6% | 826,653 | 1,678 |
| 10 | Norfolk CountyGEOID 25021 | 396.1 mi² | 48.2 mi² | 10.9% | 739,749 | 1,868 |
| 11 | Barnstable CountyGEOID 25001 | 394.2 mi² | 911.4 mi² | 69.8% | 233,539 | 592 |
| 12 | Dukes CountyGEOID 25007 | 103.2 mi² | 387.8 mi² | 79% | 21,219 | 206 |
| 13 | Suffolk CountyGEOID 25025 | 58.3 mi² | 62 mi² | 51.5% | 791,891 | 13,593 |
| 14 | Nantucket CountyGEOID 25019 | 46.2 mi² | 257.5 mi² | 84.8% | 14,758 | 319 |