Canada
Canada Postal Code Format Explained
Understand the Canadian postal code pattern A1A 1A1: letters and digits, the forward sortation area, unused letters and common entry mistakes.
Updated 14 October 2026 · 3 min read
A Canadian postal code has six characters in the pattern letter, digit, letter, space, digit, letter, digit. The generic form is A1A 1A1. Letters are always uppercase in official use, and the space in the middle is part of the standard way of writing it.
The two halves
| Part | Characters | Name | Role |
|---|---|---|---|
| First half | A1A | Forward sortation area (FSA) | Region for first-stage sorting |
| Second half | 1A1 | Local delivery unit (LDU) | Smaller delivery area |
The forward sortation area ties the code to a geographic region where mail is initially sorted. The local delivery unit narrows it down: in a city it may identify one side of a street segment, a large building or an organization that receives a lot of mail. In a rural area it covers a wider region.
What the first letter tells you
The first letter relates to a province, territory or part of one. Some provinces use several letters, because they have many postal districts, while a few places share a single letter. The second character of the code, a digit, is often a zero for rural areas and another digit for urban ones. This is useful background, but you should not try to infer the province from the code in software; rely on the province the customer provides.
Letters that are not used
To reduce reading errors, six letters are never used: D, F, I, O, Q and U. The letters W and Z do not appear as the first character. If a code you have been given contains one of these in the wrong place, it is most likely a typing mistake, for example an O typed instead of a zero.
Valid format examples
These values illustrate the pattern only and are generic:
A1A 1A1B2B 2B2C3C 3C3
Common mistakes
- Mixing zero and the letter O. Because O is not allowed, a zero is always the digit.
- Missing or doubled space. Systems usually accept the code without a space, but people expect to see it. Normalize to uppercase with one space.
- Swapping the pattern. The digit and letter positions alternate; a code starting with a digit is not valid.
- Using lower case in a form. It is easy to accept and convert, so do not reject it.
For lookup help, see how to find a postal code in Canada. For the overall address layout, see Canada address format, and for an exact point see the country overview.
Frequently asked questions
How many characters is a Canadian postal code?
Six characters, alternating letter and digit, written as two groups of three separated by a single space, for example A1A 1A1.
Are all letters used in Canadian postal codes?
No. The letters D, F, I, O, Q and U are not used, to avoid confusion with digits and other letters. W and Z are also not used as the first letter.