PST – Pacific Standard Time


Everyone has heard about time zones, but not many people know exactly why they were created and why they are important. It is only proper that a brief history about time zones be told, and next, we’re going to dig deeper and discuss PST, the Pacific Standard Time, widely used in North America.

The History of Time

A few centuries ago, every country, city, and town of the world was actually on its own time. Time varied across short distances, and there were no time standards. In the United States alone, there were more than 300 local times during this period. What usually was the ‘standard’ was, in many cases, a clock tower or large clock placed in strategic places in these locations where everyone could see it. An example of these large clocks was the Time Bell (Zytglogge Tower) in Switzerland. The sun was used to measure time, with people telling the time using sundials. 

As time went by, and around the 17th century, some other tools such as pendulum clocks came onto the scene. One of the drawbacks of the pendulum clock, however, was that it could not accurately measure time for scientific purposes and could not also sufficiently determine longitude at sea.  Then in 1764, an English horologist, named John Harrison, invented the clock that could be used to determine the location of a ship at sea. His discovery became the foundation upon which Act 5 George III (the Longitude Act) was built: the same longitudinal concept that we still use today.

Although the Longitude Act made it easier to locate ships at sea at the period, the heightened need for an efficient, time-saving system of telecommunication and the expansion of various means of transportation in the 19th century became a stumbling block. Time calculation also became a severe problem for long-distance travelers. The reason for this was simple—many trains were scheduled to operate at specific times for both departure and arrival. The need for a better and unified timing-keeping system became not only noticeable but urgent. 

It was Sir Sanford Fleming, in 1878, who first proposed the idea of using international time zones. He was mainly instrumental in having a unified world timing system by helping to convene the International Meridian Conference.  He explained that since the earth rotates 15 degrees every hour (or 360 degrees in 24 hours), dividing the world into 24 time zones that were each 15 degrees of longitude apart made sense. With time, Fleming’s proposition became widely accepted. Also, around the time Fleming’s idea became popular, Britain had already begun using their own timing system, taking their point of origin to be the Greenwich Meridian. At that time, the Greenwich Meridian was the most popular among the various meridians used for longitudinal references among different countries, and many people unofficially see the Greenwich Meridian as the prime meridian. Two reasons were responsible for this wide acceptance of the Greenwich Meridian, namely:

  • The dependable and accurate data that the Greenwich Observatory regularly presented.
  • Britain, at the time, had many means of transportation, majorly ships, using the Greenwich Meridian than the rest of the world put together, and the British Nautical Almanac have been working on charts for a long time. 

Then in 1884, at the International Meridian Conference in the United States, it was unanimously decided that Greenwich, England, would act as the Earth’s prime meridian and the Greenwich Mean Time (GMT) as the entire world’s time standard. Additionally, the 24 time zones would be based on this location (Greenwich, England, was agreed to be the prime meridian, which refers to zero degrees longitude). Therefore, all time zones in the world referred to the GMT zone and the prime meridian to ensure a fully synchronized time standard, giving us what we have now: the 24-hour international time zones.

After the adoption of the GMT by the International Meridian Conference, some states in the United States began to use the time zones. But the use of time zones in the U.S. never became compulsory until March 19, 1918, when Congress passed the Standard Time Act. However, in 1972, Coordinated Universal Time (UTC) became the world’s time standard, replacing the GMT. Since that time, the different time zones have always been calculated based on their relation to the UTC.

A time zone is basically a region of the globe where the same standard time is used. In other words, all the countries in a time zone keep the same time. The local time within a time zone is defined by its difference from Coordinated Universal Time (UTC): the world’s time standard. For UTC,  time changes 1 hour forward and backward equivalent to a 1-hour difference in mean solar time for every 15 degrees east or west of the prime meridian( with a longitude of zero degrees) in Greenwich, United Kingdom. The difference is expressed as either UTC- or UTC+ and the number of hours and minutes.

It is very important to note that times zones are very useful for commerce because they help countries that are close to each other to keep the same time. Communication becomes much easier when both parties are in the same time zone. In addition, time zones are important for military operations. 

What Is PST?

PST (also known as Pacific Standard Time or simply Pacific Time) is 8 hours before Coordinated Universal Time (UTC). This means that to get the correct time in the zone, you must subtract eight hours from Coordinated Universal Time (UTC). UTC is the primary time standard on Earth, which means it regulates all of the other time standards. In other words, all of the different time zones are an offset of the Coordinated Universal Time. It is important to note that PST has two major names: Pacific Standard Time and Pacific Daylight Time. 

Pacific Standard Time, as we mentioned earlier, is UTC-8 (8 hours before UTC). On the other hand, Pacific Daylight Time is UTC-7 and is used only during daylight saving time. Daylight Saving Time is observed during the summer months and is designed to increase the time humans can be active during daylight.  Daylight Saving Time starts on the second Sunday of March and ends on the first Sunday of November. It starts and ends at 2 in the morning (AM). 

Although time zone is different from local time, many people often confuse the two terms with each other. For instance, the standard time in California is UTC-8, but the local time during DST is UTC-7. Arizona, on the other hand, always has a UTC-7 local time, since there is no DST in Arizona. Their standard time is constant throughout the year. Therefore, it would be incorrect to say both states are in the same time zone. What really happens is that California and Arizona have the same local time during DST.

The Mechanism Of Pacific Standard Time

Now you already know what PST is and how it relates to the Coordinated Universal Time (UTC). But still, many people find it confusing to convert PST to different time zones. The reason is that they don’t fully understand the mechanism of Pacific Standard Time. 

It’s especially problematic for people who work or live in some states of the US or Canada that have a habit of changing their clocks depending on the time of year. Different time zones can be puzzling for communicating meeting times but no one wants to disappoint their employers or colleagues. It’s even more complicated with the states that observe Daylight Saving Time change their clocks in the spring or the fall. That’s why it’s important to find out how various time zones work. 

Long story short, Pacific Standard Time (PST) is 8 hours behind the Coordinated Universal Time which is standard in many countries and territories, written as UTC – 8. Therefore, in order to avoid confusion, the best way is to use our Time Zone Converter, find the standard time in your preferred zone, and convert it to UTC. Afterward, you should subtract eight hours in order to adjust the time according to PST. 
However, keep in mind that territories that use PST also observe Daylight Saving Time. It’s called Pacific Daylight Time (PDT) in the US and Canada and Zona Noroeste (Northwest Zone) in Mexico. During PDT a time offset is UTC – 7 hours.

How to Convert PST to Other Time Zones?

Today there are various online resources on the internet that can help you convert specific times to different time zones. In the past, people had to undergo complex calculations in order to determine the exact time in some places of the world but now the situation is much easier. In fact, you can just use resources such as our Time Zone Converter to convert PST to other time zones.

But if you want to learn how to convert Pacific Standard Time to different time zones, here’s a small guide that you can follow wherever and whenever you are:

  • PDT is 1 hour behind Mountain Daylight Time (MDT).
  • PDT is 2 hours behind Central Daylight Time (CDT).
  • PDT is 3 hours behind Eastern Daylight Time (EDT).

Therefore, in order to convert PDT to MDT, you should add one extra hour; In order to convert PDT to CDT, you should add two hours, and convert PDT to EDT, just add three hours. 

Also, pay attention that 

  • PDT is two hours ahead of the Hawaii–Aleutian Time Zone.
  • PDT is one hour ahead of the Alaska Time Zone.
  • PDT is one hour behind the four hours behind the Atlantic Time Zone.

Countries That Are in Pacific Standard Time

PST covers the United States, Canada, and Mexico but not in their entirety. In the United States, the Washington and California states are entirely in Pacific Standard Time. Most of the Oregon and Nevada states are also in PST, while just portions of Idaho are included in this time zone. These three states are split between PST and Mountain Time Zone. Alaska is also split between PST and the Alaska Time Zone.

In Canada, only one territory is entirely in PST: Yukon. British Columbia and the Northwest Territories are split between PST and the Mountain Time Zone.

In Mexico, Pacific Standard Time encompasses just Baja California and Colima (Clarion Island more specifically). It is important to note that in Mexico, the Pacific Time Zone is called Zona Noroeste.

Important Cities in PST

According to estimates, more than 52 million people live inside the PST time zone. California is by far the biggest area in PST, with three major cities: San Diego, Los Angeles, and San Jose. San Francisco is also in PST, with more than 700,000 residents. Las Vegas, Portland, and Seattle are the three other major American cities that are in the Pacific Time Zone. 

In Mexico, Baja California, and Tijuana are in PST, while in Canada Vancouver is the major city that contributes around 400,000 residents to the total number of people residing in the PST time zone. If you think 52 million people are a lot for a time zone, think about China. China has a single time zone, and the country has a population of 1.38 billion people as of 2016. India has a single time zone as well. Russia on the other hand is split between 9 time zones. It should have been split between 12 time zones, but president Putin decided 3 of the time zones must go to bring some areas of Russia closer to the Moscow time.

Pacific Daylight Time

Similar to Central Daylight Time (CDT) or Eastern Daylight Time (EST), territories in the PST time zone seasonally observe Daylight Saving Time during the spring and summer and it’s called Pacific Daylight Time (PDT). 

PDT is the westernmost time zone in the United States, Canada, and Baja California, one of the states of Mexico. This time zone spans from Canada to Mexico and is considered the third most populated time zone together with PST. Similarly, PDT shares a border with MST in the east. 

Pacific Daylight Time has operated since 2006 when the local time (PST, UTC – 8 hours) was first changed to daylight time (PDT, UTC−07 hours) at 2. a.m. on the first Sunday in April. It returned back to standard time and switched from 2 a.m. to 1 a.m. on the last Sunday in October 2006. The law became official in the USA in 2007 by the Energy Policy Act of 2005. Canadian provinces and states started observing daylight saving time between October 2005 and February 2007. 

Mexico adjusted the DST later, at the beginning of 2010. However, certain parts of the country still use standard time in all seasons. Daylight Saving Time in Mexico follows the same schedule as in the United States and Canada. However, its official name is Zona Noroeste that translates in English as Northwest Zone. 

Today the seasonal shift from PST to PDT is a little bit different from the time it was initiated. Specifically, PDT starts on the second Sunday in March and continues to the first Sunday in November.

PST vs PDT – Comparison

As you can see, it’s nothing difficult to differentiate PST and PDT from each other but since there are so many time zones in the world today, people still tend to get confused about this matter. That’s especially common after Daylight Saving Time starts and they have to change their clocks accordingly. Some of them may not know the exact difference between standard and daylight time, others may be confused whether to switch their clocks one hour forward or backward, etc. In this section, we will provide the exact differences between these two time zones and help you understand when to use them. 

First of all, it’s important to point out that both PST and PDT are parts of the Pacific Time Zone (PT). Pacific Time Zone includes 25 time zones and covers certain parts of Canada, the United States, and Mexico. These territories observe both PST and PDT but use them in different seasons. 

PST stands for Pacific Standard Time. It’s used during the fall and the winter and is eight hours behind the Coordinated Universal Time (UTC). On the other hand, PDT is an abbreviation of Pacific Daylight Time and is used in the spring and summer. PDT is seven hours behind the Coordinated Universal Time (UTC). So, remember that

  • Both PST and PDT are observed in territories of the Pacific Time Zone (PT).
  • PST continues from Early November to Mid March; PDT continues from Mid March to Early November.
  • PST is It is the standard time and it remains the same. PST is one hour ahead of PST.

Interesting Time Zone Facts

Now that you know that UTC and the UTC offset are, and how PST fits into the picture, it’s time to take a look at some of the most interesting facts about time zones: 

  • It is important to note that broadcasting companies are directly affected by time zones. North American broadcasters must take into consideration the various time zones and schedule television programming accordingly. Another variation is given by the daylight saving time.
  • Some countries use an offset that is multiple of 30 minutes. While most people think that time zones are determined by whole hours, several countries in Southern Asia (India, to be more specific), are in the UTC+5:30 Time Zone, or 13 hours and 30 minutes ahead of PST. Iran is UTC+3:30 and Afghanistan is UTC+4:30. And to make things even more complicated, Nepal is UTC+5:45.
  • UTC+12 and UTC-12 are the same time zone, but with a different date. The difference between countries in these two time zones is of 24 hours, or one whole day.
  • One could have two birthdays in 24 hours by travelling between different time zones. Also, one could skip Christmas doing the same. There are areas where a quick flight can force people to adjust their clocks with as much as 4 hours.
  • Russia spans over 11 time zones geographically. However, Putin decided to abolish two of them in 2010 so that several regions could catch up with Moscow and be on the same time as the capital city. Also, Crimea skipped ahead two hours when it was annexed by Russia in 2014.
  • India is a huge country that maintains a single national time zone, which is UTC+5:30. And Hawaii doesn’t adhere to Daylight Saving Time at all. The time zone of Hawaii is GMT-10 all year round.
  • Remember that your wristwatch will not know when you are in a different time zone, so you will have to adjust it manually. Your computer and your smartphone, on the other hand, are capable of adjusting their time accordingly automatically.
  • Jet lag is caused by the time zone differences. When you travel quickly between various time zones, the time zone differences will disturb your circadian cycle. You may leave early in the morning and when you arrive at the destination, it can be late at night. Your body will take some time to get used to this.
  • Did you know that the United Kingdom, who has invented GMT (Greenwich is in the UK), is not in the GMT time zone all year round? British observe Daylight Saving Time, which means that they are actually in BST (which is UTC+01:00) during the summer months. They are in GMT though during the winter months.
  • Only two states in the United States that do not follow daytime saving time are: Arizona and Hawaii. In Arizona, particularly, daylight heat can be so intense that many residents schedule their outdoor activities to the evening hours when it is much cooler.
  • An island in the Baltic Sea, called the Island of Market, follows two time zones. This is because the island is controlled by Finland and Sweden. The part of the island conr9lled by Sweden is follows Swedish local time and the other half follows the local time in Finland.
  • North Korea in August 2015 decided move back to its original time zone (GMT-8:30) which was used before the Korean liberation from Japan.
  • Contrary to popular belief, daytime saving time was not created to support farmers. In the United States, for instance, farmers never supported daytime saving time. The proponents of daytime saving time were business owners, so they could take advantage of summer daylight.
  • North Pole and South Pole have no official time zones because all the longitude lines meet at the poles.
  • France has the highest number of time zones in the world with a total number of 12. This is as a result of territories still being held by France across the world, such as French Polynesia (UTC-10) to Wallis and Futuna (UTC+12)
  • Spain is in the ‘wrong’ time zone. This is because most of mainland Spain is either on the same longitude as or further west than the UK. Yet, Spain is an hour ahead time-wise.
  • In Samoa, December 30, 2011 didn’t exist when the country decided to skip an entire day to officially move into the adjacent westward time zone. This was done to align their time with closer countries like Australia, Singapore, and China which are all on GMT-11.
  • Many countries do not observe daylight saving time. Examples are most of the countries in Middle East, South America, Asia (such as Japan, Indonesia, Thailand). Africa (with the exception of Namibia, Egypt, Tunis, and Morocco). Although South Australia observe daylight saving, Northern Territory, Queensland, and Western Australia do not. 
  • The International Space station (ISS) uses the GMT.