Zip Code 01821 — Billerica, MA
01821 is a ZIP Code associated with Billerica, MA, located within Middlesex. The postal region supports an estimated population of 30,143 residents across Data Pending housing units, with a population density of 701.4 people per square mile.
WorldPlaceData database updated: October 2026
📍 View location on OpenStreetMap (42.549990, -71.252060)
| Data Metric | Local Statistic |
|---|
| Postal / Zip Code | 01821 |
| Primary City | Billerica |
| State / Province | MA |
| County | Middlesex |
| Total Population | 30,143 |
| Median Household Income | Data Pending |
| Total Housing Units | Data Pending |
| Population Density | 701.4 people/sq mi |
| Timezone | America/New_York |
How 01821 Compares
| Metric | ZIP 01821 | Middlesex County | MA State Average |
|---|
| Population | 30,143 | 1,629,277 | 7,043,978 |
| Median Income | Data Pending | N/A | N/A |
| Population Density | 701.4 /sq mi | -- | -- |
Nearby ZIP Codes
Data Sources & Methodology: Geographic coordinates and ZIP Code assignments are derived from underlying geographic and postal datasets. Note that ZIP Codes are USPS postal delivery areas, while Census ZCTAs are statistical approximation areas. Read full methodology →