Official time in Canada is the second kept by the National Research Council in Ottawa, tied to Coordinated Universal Time. Legal time — the hour a school, court, or bus schedule uses — is set by provinces and territories. A phone can disagree with both for a while after a law changes, because phones follow a software database, not a statute. Those three layers are the whole system.
The rest of this page is who keeps the official second, how that second reaches the public, why the NRC does not choose your time zone, and what “on time” means when those layers drift apart.
Who keeps official time in Canada?
The National Research Council is the federal agency responsible for official time. Metrologists in its frequency and time group run an ensemble of atomic clocks at the time standards laboratory in Ottawa. The scale they produce is called UTC(NRC). It is Canada’s realization of Coordinated Universal Time, the international reference used by national labs around the world.
That role is older than the current lab branding. Civil time signals in Canada began with astronomers. An order-in-council in 1941 named a federal scientific body as the source of official time. In the early 1970s the work moved from the Dominion Observatory tradition to the NRC, where it sat with atomic frequency standards instead of with the night sky. The institution changed. The job did not: keep a second that other clocks can trust.
The NRC does not run the clocks in every kitchen. It keeps the reference. Everything else is a copy, a broadcast, or a legal label applied to that reference.
How does an atomic clock become “the time”?
A cesium atomic clock does not tell 3:00 p.m. in the sense a wristwatch does. It counts a physical frequency. The international definition of the second is a fixed number of oscillations of a cesium-133 atom. The clock measures those oscillations and, after that count, one second has passed.
One clock is not enough. The Ottawa laboratory runs a group of clocks and compares them continuously. Individual clocks wander by a few nanoseconds. An average of the ensemble is more stable than any single unit.
Over a year, the official scale is kept to about a microsecond. No person needs that precision. Inside the lab, the clocks are compared much more tightly than that.
UTC(NRC) is then compared with other countries’ official scales so that Canada’s second stays inside the international UTC system. Official time in Canada is not a private national invention. It is a national copy of a shared scale.
When daylight saving time starts or ends in a province that still uses it, the NRC does not open the cesium clocks and turn a dial. The atomic ensemble keeps running. Only the time sent out to the public is stepped by one hour on the broadcast and telephone services that announce civil time.
What is UTC, and how is it different from the time on the wall?
Coordinated Universal Time is the modern successor to Greenwich Mean Time as a world reference. Canadian legal texts that still say “Greenwich” are read as UTC. Time zones are written as offsets from that scale: Atlantic Time is four hours behind UTC in winter, Newfoundland Time is three and a half hours behind, and so on.
UTC is not a place you can stand. It is a paper and laboratory scale. Noon UTC is not solar noon in Ottawa or in Greenwich in the old sense. Civil clocks in Canada are UTC plus or minus a whole number of hours — or, in Newfoundland, plus or minus a half hour — as each province’s law requires.
Two other scales sit in the background. International Atomic Time is a pure atomic count with no leap seconds. Earth rotation time, often called UT1, follows the planet as it speeds up and slows down by tiny amounts. UTC is atomic time with occasional one-second adjustments, called leap seconds, so that it does not drift far from Earth rotation. The NRC publishes the difference values used by navigators and surveyors. None of that changes the hour a store prints on its door.
How does official time reach the public?
The NRC sends the same official second out through several channels. They differ in convenience, not in the source.
Shortwave station CHU used to broadcast the official signal from a site southwest of Ottawa, on 3.330, 7.850 and 14.670 megahertz. That radio service ended in June 2026. American stations WWV and WWVH can still be heard in Canada on shortwave. The NRC’s official second is now reached through the web clock, the telephone talking clock, and Network Time Protocol.
A telephone talking clock in Ottawa announces Eastern Time every ten seconds, then a tone. The English line is 613-745-1576. The French line is 613-745-9426. The call cuts off after a few announcements. From outside the local area, ordinary long-distance rates may apply. The voices are recorded. They are not a person sitting by a microphone all day.
CBC Radio has long carried an NRC time signal once a day on its main networks. That beep is the version most people have heard without knowing the lab’s name.
Computers and servers can use Network Time Protocol. The public NRC host names are time.nrc.ca and time.chu.nrc.ca. They are not websites. They are stratum-2 time servers steered by the same atomic clocks, meant for clock-sync software. A home computer that “sets time automatically” usually talks to a pool of NTP servers, which may or may not be these two. Banks, broadcasters, and federal systems that need a traceable Canadian source use NRC time on purpose. Shared Services Canada’s enterprise time service is one federal example: it takes an NRC feed and hands it to government networks.
The NRC also runs a web clock that displays official time by zone and shows how far a visitor’s device has drifted. That page is a demonstration of the reference, not the law that names your zone.
Who decides the hour on the wall?
Provinces and territories. Official time answers “how long is a second, and what is the time at the reference?” Legal time answers “when we say 9:00 a.m. here, which offset from UTC do we mean?”
Zone boundaries, daylight saving, and year-round locked offsets are written in provincial and territorial statutes and regulations. The NRC publishes maps and notes that a major change in official practice will be recorded. It does not pass those statutes. Saskatchewan can stay on Central Standard Time all year. Yukon can stay on UTC−7 all year. British Columbia can rename a locked offset Pacific time. Ontario can keep springing forward. None of that requires the cesium ensemble to change its count.
Municipalities can sit on an exception inside a province. Atikokan in Ontario and Blanc-Sablon in Quebec are examples. Those exceptions are local law or local practice recognized in law, not NRC policy.
Federal offices follow the legal time of the city they are in. A midnight filing deadline in Ottawa is Eastern legal time. The same kind of deadline in Calgary is whatever offset Alberta’s statute names. The official second underneath both deadlines is still UTC(NRC).
Why can a phone disagree with official time?
Phones, laptops, and many cars take time from the network and from the public IANA time-zone database. That database is a volunteer-maintained list of civil rules. It is very good. It is not a Canadian statute.
When a province changes its time law in the middle of a year, two things happen on different clocks. The NRC keeps counting seconds. The province’s legal offset changes on the date the law names. Phone makers and app vendors then ship a database update. Until that update arrives, a lock screen can show last year’s rule.
A large error on a device is usually a wrong zone setting, not a wrong official second. If the NRC web clock and a phone differ by an hour, the phone’s zone or daylight-saving flag is the first place to look. If they differ by a few seconds, the device is ordinary. If they differ by minutes and the zone is correct, the device is not synchronizing.
GPS time is another copy. Satellite clocks are steered toward official time, with known offsets. A phone that uses GPS for location is not, by itself, displaying UTC(NRC).
What official time is for
People use legal time to meet. Official time is for systems that have to agree when “the same moment” was.
Telecom networks, power grids, broadcast transmitters, and financial time-stamps need a shared second. Navigation and surveying need a second that can be traced to a national lab. Science needs a second that matches the SI definition. The NRC’s job is that shared second. The provincial job is the label printed on the meeting invite.
Those purposes explain the precision. A bus driver does not need a microsecond. A network that stamps millions of packets does.
A short history, only as far as it helps
Standard hour zones in Canada descend from nineteenth-century railway practice and from Sandford Fleming’s campaign for a worldwide hour grid. That history explains why most zones are one hour wide and why Newfoundland’s half hour looks odd. It does not explain who keeps the second today.
Astronomers once defined official time from Earth rotation and the position of the sun. Atomic clocks replaced that definition because atoms repeat more steadily than the planet turns. Canada followed that shift when official time moved into the NRC’s frequency work. The talking clock and the radio beep are the public remnants of the older service. The lab behind them is an atomic one.
Common mistakes
The NRC does not “change the clocks” for Canada each March. It keeps the second. Provinces that still use daylight saving change the civil label applied to that second.
UTC is not “the time in England.” It is a laboratory scale. London’s legal clock is an offset from UTC, the same as Halifax’s.
A phone that updates itself is not reading a provincial gazette. It is reading a database that usually tracks the gazette, after a delay.
“Official time” and “the correct time where I live” are not synonyms. Official time is the second. The correct time where you live is that second plus the offset your legislature named.
Limits
This page describes the standing system: NRC as official timekeeper, UTC as the reference, provinces as authors of legal time. Service details — a telephone number, an NTP host name, a CHU frequency — can move. If you need the signal itself, use the current NRC time-services page.
Leap seconds and a possible future redefinition of the SI second in terms of an optical clock are live topics in metrology. They do not change how a Canadian court dates an affidavit this year. They are reasons the laboratory exists, not reasons to reset a kitchen clock.
Short wrap
Canada keeps official time in an Ottawa laboratory, as UTC(NRC), counted by an ensemble of atomic clocks and sent out by radio, telephone, and internet time servers. Provinces and territories decide which offset from that scale is legal on the street. A phone is a third copy, usually close and sometimes late. If you want the second, look to the NRC. If you want the hour on the wall, look to the law where you live.
SOURCES: National Research Council Canada; Shared Services Canada; Canadian Encyclopedia; public NRC time-service and frequency-and-time pages.
