Time Zones - Overview

Time zones… while there are some who think time zones should be eliminated altogether and the entire globe should transition to all clocks set to UTC (the Mr. is one of them, don’t get him started!), the reality is that they are here… seemingly to stay… and we have to use them.

Clock tower with astronomical clock in Bern, Switzerland

Time zones are especially important to the TRW lifestyle since the main crux of the lifestyle is being in any time zone desired while still working a specific set of hours in a specific time zone. Time zone math is essential to do accurately! It can be complicated, don’t get me wrong. But there are tools we use to make TRW lifestyle and time zone math easier on ourselves. Plus, there are added benefits that come from being in a different time zone than you work in!


Let’s start with an introduction to time zones and notation. Before we started traveling, I thought there were only 24 time zones using universal names, hourly increments, and nice (approximately) vertical lines to define everything. Ha! Boy was I wrong! While there are actually only 24 clock hours, the time zones can extend to more than 12 zones (both moving east and west from the Prime Meridian), therefore overlapping identical times but one with a “UTC -” and another with “UTC +” over the International Date Line. Additionally, there are some time zones that have a 30 minute off-set, and even a few crazy places that have a 45 minute offset!


For a bit of history, in case you didn’t know, time was not something that magically lined up into the coordinated system we use today (no matter how you feel about time zones). In 1884 important people decided that there needed to be a standard timing scheme and Greenwich Mean Time (GMT) would start everything off. This meant that The Prime Meridian, 0* longitude, was set as the line that went through the telescope at the Royal Observatory in Greenwich, London. All time would be set according to this point and thus began the 24-hour time system we are familiar with today.

Royal Observatory Greenwich in Greenwich, London, UK

Things got messy along the way with accuracy and daylight savings issues. In the 1960s, other smart people started talking about a more formal universal time set by super cool and accurate instruments (like ones that could account for leap seconds - it’s a thing!) and officially adopted the Coordinated Universal Time in 1967. Coordinated Universal Time is abbreviated as UTC. Yes, this does not match. There was actually a lot of reasoning (read: likely committee decision) put into choosing UTC. It basically boils down to Coordinated Universal Time does not have the same letters when translated into other languages so they chose UTC because it was close enough in all of them no one would get their feelings hurt … ish. Once the new system was in place, GMT was the same as Universal Time. After 1972, GMT as a concept of standard time phased out and has been just a regular time zone.

So, Universal Time is a time standard, UTC / +0000 is still set at the Prime Meridian but doesn’t necessarily go through the telescope, UTC = GMT, but GMT is just a regular time zone but also sometimes still used interchangeably with UTC in primarily English speaking countries. And finally, not to make it any more confusing, Greenwich, London observes daylight savings so it doesn’t even use GMT all year round! Clear as mud, right?


My FAVORITE website to use to do all the time zone math is www.timeanddate.com. You can search for countries or specific cities (which is what I do to make my charts to be as accurate as possible). There is all kinds of information about if the place observes daylight savings, when the changes happen, historical information on daylight changes, and even weather and sun / moon data.

I enjoy looking at the map view to both get a good overview / big picture idea of our specific trip block (US -> other places -> US loop), but also what the rest of the world is doing! The map view has the different UTC off-set zones and highlights the countries that have the same offset when you mouse over. There are a handful of cities featured, too, that provide information when moused over. I like to see how all the pieces fit together.

This website has all kinds of other cool stuff on there that I haven’t used, but it may be helpful for you.

Back To Time Zone Math

But really, this is helpful to have a basis of how to do your time zone math. I refer to everything in UTC off-sets. This is helpful because there are often many time zone labels for the same UTC off-set. For example, Eastern Daylight Time (EDT), Atlantic Standard Time (AST), Amazon Time (AZT), and Chilean Standard Time (CLT) are all UTC -4. [Note: I like to understand how it all connects, but I don’t usually try to understand WHY they are what they are. Those four time zones I listed all have the ‘same time’ …. but only some portion of the year and other times they can be two hours different, and they do not all line up along similar longitude regions…. I’m sure there are lots of politics that go into these decisions. It’s best not to think about it too much.]

Depending on where we’re going, I make either a simple chart to do conversion or a super complicated chart mapping every single day we are gone in a trip block. But, time zone math isn’t always bad. Being in different time zones shifts your day-parts and can allow you to actually have more time to have fun!

Our Articles

I could go on and on just about time zone math! Below is a compilation of all kinds of time zone related articles to help you both travel, but also live the TRW lifestyle.

  • Time Zones: Today / Tomorrow Time Zone Conversion Chart (still to come)

  • Time Zones: Day-to-Day Travel Time Change Chart (still to come)

  • Time Zones: Eight-hour blocks (still to come)