Postal Codes in Ontario
Ontario's postal codes cover Canada's most populous province by a wide margin, home to around 15.6 million residents, more than a third of the country's entire population. Toronto anchors an enormous metro area that serves as Canada's financial and cultural capital, while Ottawa, the national capital, sits further east along the Ontario-Quebec border.
How Postal Codes Are Organized Across the Province
Ontario's postal codes use several leading letters given the province's huge population - M for Toronto proper, L for the surrounding Greater Toronto Area suburbs, K for Ottawa and eastern Ontario, N for southwestern Ontario including London and Windsor, and P for the vast, sparsely populated north.
Ontario's Major Cities by Population
The chart below shows just how dominant the Toronto metro area is within Ontario's overall population, dwarfing every other city in the province.
Toronto's postal codes cover Canada's largest city and financial capital, home to the country's main stock exchange and a huge share of its banking and corporate headquarters activity, alongside one of the most ethnically diverse populations of any city in the world. Ottawa, the national capital, carries a strong government employment base alongside a growing tech sector, sometimes referred to as "Silicon Valley North." For a broader comparison, our full ZIP and postal code directory shows how Ontario's system fits alongside other regions we cover.
Southwestern Ontario and the Golden Horseshoe
The Golden Horseshoe region, wrapping around the western end of Lake Ontario from Hamilton through the Greater Toronto Area, is Canada's most densely populated and industrialized corridor. Further southwest, London and Windsor anchor a region with strong ties to the automotive industry - Windsor, directly across the border from Detroit, has been a major auto manufacturing hub for over a century.
Northern Ontario
Northern Ontario stretches across a vast, sparsely populated expanse of boreal forest and mining country, a sharp contrast to the dense urban corridor further south. Cities like Sudbury and Thunder Bay serve as regional hubs for mining and forestry industries, and postal codes here cover enormous geographic areas relative to their population, similar to remote regions found in Minnesota and Michigan's Upper Peninsula just across the border.
Why Postal Codes Matter Beyond Mail
In Ontario, postal codes carry enormous weight in the Toronto real estate market, one of the most expensive in North America, where boundaries can signal significant differences in commute time and school district quality. The automotive industry around Windsor and southwestern Ontario relies on postal-code-level data for supply chain coordination with Michigan just across the border. And Ottawa's federal government presence means postal codes there see particular significance for civil service employment and policy analysis.
Finding the Right Postal Code
Use the list below to browse Ontario's postal codes by city, region, or population - sorted so the most populous areas surface first. Each entry links through to a detailed page with additional demographic data. If you're trying to identify the postal code for a specific address rather than browsing by city, the search tool at the top of this page will get you there faster than scrolling through the full list.
Frequently Asked Questions
How many postal codes does Ontario have?
Ontario has tens of thousands of postal codes, more than any other Canadian province, reflecting its status as the country's most populous province by a wide margin.
What letters do Ontario postal codes start with?
Ontario uses several leading letters given its large population, including M for Toronto, L for the Greater Toronto Area, K for Ottawa and eastern Ontario, N for the southwest, and P for the north.
Which Ontario city has the most postal codes?
Toronto and the surrounding Greater Toronto Area account for the vast majority of the province's postal codes, given how heavily Ontario's population concentrates there.
Can I look up an Ontario postal code by city name?
Yes, use the search tool on this page or browse the full list below, which is organized by city and sorted by population.
Whether you're relocating to Toronto, researching property near Ottawa, or simply trying to pin down the right postal code for a specific Ontario address, the data below covers every corner of the province.