Canada Postal Code Format — How Canadian Postal Codes Work

Canadian postal codes use a unique alternating letter-digit format — A1A 1A1 — that encodes geographic information far more precisely than most postal systems. With roughly 850,000 active codes, Canada's system can pinpoint delivery down to a single city block, apartment building, or even a large-volume mail receiver.

The A1A 1A1 Format

Every Canadian postal code is exactly six characters long, written with a space in the middle: A1A 1A1. The characters alternate between letters and digits in a strict pattern:

The letters D, F, I, O, Q, and U are never used in any position to avoid confusion with digits (0, 1) and other characters. The letters W and Z are not used as the first character.

FSA — Forward Sortation Area

The first three characters form the Forward Sortation Area (FSA). This identifies a broad geographic region:

• First letter — identifies the province or territory (see table below)
• Second character (digit) — 0 indicates a rural area; 1-9 indicates an urban area
• Third character (letter) — further narrows the geographic zone within the province

There are approximately 1,600 active FSAs across Canada. In urban centres like Toronto or Vancouver, a single FSA may cover just a few city blocks. In rural areas, an FSA can span hundreds of square kilometres.

LDU — Local Delivery Unit

The last three characters form the Local Delivery Unit (LDU). This narrows the location to a specific delivery point:

• In urban areas, the LDU typically identifies a single block face (one side of a street between two intersections), an apartment building, or a large commercial mail receiver
• In rural areas, the LDU corresponds to a community mailbox group or rural route

The combination of FSA + LDU means each postal code serves a very small area — often just a few dozen addresses.

Province Prefix Letters

The first letter of a Canadian postal code identifies the province or territory:

Note: Ontario and Quebec are large enough to have multiple first-letter assignments, reflecting their high population density and mail volume.

How to Read a Canadian Postal Code

Let's decode the postal code M5V 2H1:

• M — Metropolitan Toronto, Ontario
• 5 — Urban area (non-zero digit)
• V — Specific zone within the M5 area (downtown core / Entertainment District)
• 2H1 — Local delivery unit narrowing to a specific block or building

Compare with S0K 2E0:

• S — Saskatchewan
• 0 — Rural area (zero digit)
• K — Zone within rural Saskatchewan
• 2E0 — Specific rural delivery route

Difference from US ZIP Codes

Examples by Province

Frequently Asked Questions