ZIP Code 63303

63303 is one of Missouri's ZIP codes, delivering to addresses in Saint Charles, St. Charles County.

City: Saint Charles
County: St. Charles County
State: Missouri
Prefix: 633xx

Where this code sits

63303 is part of the 633xx range, the group of codes handled by one mail processing centre. Saint Charles is served by 4 ZIP codes in total.

Area codes over the same ground

Postal and telephone geography are drawn separately, so these codes cover the area 63303 delivers to without sharing its boundary.

ZIP codes nearest 63303

The ZIP codes whose reference points sit closest to 63303.
ZIP code	Distance	Delivers to
ZIP code 63346	1.0 mi	Flinthill, MO
ZIP code 63301	3.5 mi	Saint Charles, MO
ZIP code 63302	3.9 mi	Saint Charles, MO
ZIP code 63376	4.3 mi	Saint Peters, MO
ZIP code 63045	4.4 mi	Earth City, MO
ZIP code 63304	4.4 mi	Saint Charles, MO
ZIP code 63338	5.9 mi	Cottleville, MO
ZIP code 63043	6.0 mi	Maryland Heights, MO

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 63303, plotted from its record coordinates.

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

Scope ZIP code 63303. 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.