Time Zones are calibrated against the Greenwich Meridian in Greenwich, England. For decades this central time zone was referred to as Greenwich Mean Time, or GWT. More recently, however, it is referred to as Coordinated Universal Time, which is abbreviated to UTC. When observing Eastern Standard Time, Toronto's time is referred to as UTC-5, which means it is five hours behind the current time in Greenwich. Other major cities observing UTC-5 during Eastern Standard Time include Ottawa, the Canadian capital, as well as New York and Washington.
Compared to other North American time zones, Toronto is three hours ahead of western cities like Los Angeles and Vancouver, British Columbia. It is two hours ahead of cities like Denver and Calgary, Alberta. It’s an hour ahead of Des Moines, Iowa, and Regina, Saskatchewan. To the east, it’s one hour behind Halifax, Nova Scotia, and one and a half hours between all parts of Newfoundland and Labrador.
From the spring through the fall, Toronto and many other cities that observe Eastern Standard Time switch to Eastern Daylight Time. During these months, Toronto moves from the UTC-5 time zone to the UTC-4, meaning its clocks are four hours behind those in Greenwich. During this period, the time difference between Toronto and some cities in North America and other parts of the world changes, depending on whether certain areas also move to Daylight Savings Time during this period.
When observing Eastern Standard Time, Toronto is 18 hours behind Auckland, New Zealand and 16 hours behind Canberra, Australia. It’s 14 hours behind Tokyo, 13 hours behind Beijing, 10.5 hours behind Mumbai, India, nine behind Saint Petersburg, Russia and 8.5 hours behind Tehran, Iran. Toronto is seven hours behind Jerusalem, six behind both Rome and Paris, and five hours behind London. It's also five hours ahead of Honolulu.
