Canada postal code format explained: the A1A 1A1 structure
2025-02-12 · US Address Generator
A Canadian postal code has one fixed shape
Canadian postal codes are always six characters in the pattern letter-digit-letter, space, digit-letter-digit — for example M5V 2T6. The first three characters are the Forward Sortation Area (FSA); the last three are the Local Delivery Unit (LDU).
Two things follow from the structure. First, the FSA's leading letter maps directly to a province or territory, so a mismatched letter is a strong sign of a fabricated address. Second, letters and digits strictly alternate, and six letters never appear: D, F, I, O, Q and U, all excluded to avoid confusion with digits.
FSA letters by province and territory
- Newfoundland and Labrador: A
- Nova Scotia: B
- Prince Edward Island: C
- New Brunswick: E
- Quebec: G, H, J (H is the island of Montreal)
- Ontario: K, L, M, N, P (M is downtown Toronto)
- Manitoba: R
- Saskatchewan: S
- Alberta: T
- British Columbia: V
- Nunavut: X (partly shared with the Northwest Territories)
- Northwest Territories: X
- Yukon: Y
This table is the fastest validation shortcut there is: an Ontario address whose FSA starts with V is almost certainly assembled at random.
Why the space matters
Canada Post's standard requires one space between the FSA and the LDU. Many validators accept M5V2T6, but label printing and address standardization add the space back. Cover both paths in testing — one lenient, one strict — and you learn whether your form is actually strict or just pretending.
Urban versus rural
In cities an FSA covers a handful of streets. In rural areas an entire small town can share one FSA, and LDUs starting with 0 (shapes like A0A 1A0) mark route service or rural delivery. A zero in the second LDU position is a rural flag, not an error.
Correct line order
Jordan Lee ← recipient 1201 Bay Street ← house number + street Apt 908 ← unit (optional) Toronto, ON M5V 2T6 ← city, province abbr + postcode CANADA ← international only
City and province share a line separated by a comma; the postcode follows the province. Provinces use the two-letter uppercase abbreviation (ON, QC, BC, AB…), never the full name.
Common mistakes
- FSA letter that contradicts the province: the usual tell of made-up data.
- Using an excluded letter: D, F, I, O, Q and U never appear.
- Omitting the space: passes some client-side checks, fails label printing.
- Spelling the province in full: "Ontario" instead of ON breaks dropdown validation.
- Local phone formatting: international mail needs +1 and ten digits, no parentheses.
Testing with the generator
The Canada address generator covers all 13 provinces and territories and forces the postcode's first letter to match the chosen province. Use it to check three behaviours: whether the postcode resets when the province changes, whether the alternating-character regex is looser than it should be, and whether an empty unit field throws a false error.
For the full field reference, see the Canada address format guide.