[Spreadsheet] Which hour aligns most countries on the same day?

Have you ever asked yourself which hour aligns most countries on the same day? Well, I did.

Let's break down the problem first. We all understand the concept of time zones, which divide the world into different regions where local times differ, typically by one-hour increments. Because of this, some countries are ahead of you in time, meaning their clocks show a later time and they might even be in the next calendar day. Conversely, some countries are behind you, with their clocks showing an earlier time, often still in the previous calendar day. This phenomenon creates a situation where, at any given moment, different parts of the world are experiencing different times and sometimes even different days.

And instantly, with this in mind, the question "Which hour aligns most countries on the same day?" was constantly on my mind, and I really wanted to find the answer. I tried Googling for hours just to find the exact question, and I found nothing direct. I found a post on Quora, but it didn't answer what I wanted.

So, I decided to do it myself.

First things first, I would need the data that contains all the time zones, the countries that have Daylight Saving Time, and their respective months.

Steps

• Obtain all time zones
• Get and align all Daylight Saving Time rules
• Add the calculation and a custom time

Iframe | * Prefer open in a new tab below.

Open in a new tab

Based on the data, in the interval from 10:00 to 10:59 GMT+0, most countries align within the same calendar day. This hour represents a peak moment of global synchronization.

Here’s a list of the sovereign states and their respective time zones where this alignment doesn't occur:

Hour used as example: 10h30 am

Yesterday

United States (American Samoa, UTC-11:00): 23:30
New Zealand (Niue, UTC-11:00): 23:30

Tomorrow

Kiribati (Line Islands, UTC+14:00): 00:30