ZIP Code 01821

01821 is one of Massachusetts's ZIP codes, delivering to addresses in Billerica, Middlesex County.

City: Billerica
County: Middlesex County
State: Massachusetts
Prefix: 018xx

Where this code sits

01821 is part of the 018xx range, the group of codes handled by one mail processing centre. Billerica is served by 2 ZIP codes in total.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 01821 delivers to without sharing its boundary.

ZIP codes nearest 01821

The ZIP codes whose reference points sit closest to 01821.
ZIP code	Distance	Delivers to
ZIP code 01822	1.0 mi	Billerica, MA
ZIP code 01865	1.3 mi	Nutting Lake, MA
ZIP code 01866	2.0 mi	Pinehurst, MA
ZIP code 01862	2.6 mi	North Billerica, MA
ZIP code 01876	3.8 mi	Tewksbury, MA
ZIP code 01803	4.0 mi	Burlington, MA
ZIP code 01887	4.1 mi	Wilmington, MA
ZIP code 01805	4.3 mi	Burlington, MA

Straight-line distance between place reference points, not driving distance. Where a place has no Census Gazetteer point, its postal centroid is used instead.

Each point is the reference point for 01821, plotted from its record coordinates.

Reference points and footprint
Not an official NANPA boundary
Not a USPS delivery area

Scope ZIP code 01821. Source GeoNames US postal codes (2026-07 postal dump) and Census 2024 county Gazetteer (2024 Gazetteer). Updated 15 July 2026. A ZIP code is a set of delivery routes, not an area; the point shown is a record coordinate, not a centre.