How to Use the Different Bezel Scales by Extropian

Bezel scales
Slide rule
Echo Neutra
How to Use the Different Bezel Scales by Extropian

Bezels are a defining feature of many classic tool watches. But they’re not just there to look cool – they’re designed to perform very specific functions, some quite simple, others pretty complicated. We thought you‘d like to know how to use them so we’ve put together a guide. We’re nice like that!

Dive Count-Up

The Count-Up Bezel is one of the easiest to use and the most common one found on dive watches where it’s used to keep track of time spent underwater. The scale goes from zero to 60, indicating minutes in an hour. At the beginning of a dive, or whatever else you might be timing, simply rotate the bezel until the zero marker (which is generally a triangle) is aligned with the minute hand. Then, as time passes, you can use the markings along the edge of the bezel to track the elapsed time.

The first 15 minutes are usually marked in one-minute increments, allowing a diver to time decompression stops as accurately as possible at the end of a dive, while the rest of the hour is measured in five-minute increments.

Farer - Aquamatic

Farer All Aquamatic Nazare Cx Mj

Dive Countdown

A Countdown bezel works in the same way as Count-Up, but the other way around! The markers count down from 60-0, allowing you to keep track of the time remaining before or during an event. So, when the marker reaches zero it’s either about to begin or has already finished! 

Nodus - Sector Pilot  Black DLC Steel Bezel

Nodus Sector Pilot   Black Dlc Steel Bezel Phantom 09f4


A GMT bezel allows you to keep track of time in different time zones. Super useful if you’re on holiday! The scale is marked in 24 equal increments corresponding to the hours in a day and works in conjunction with an extra (GMT) hand on the dial. This means you can set the local time on the regular 12-hour dial and use the extra hand to keep track of time at home (or vice-versa).

You can also rotate the bezel forwards or backwards by the required number of hours to track a third time zone. Many GMT bezels are divided into two color zones (red for daytime, blue for night) which allow you to keep track of AM and PM.

Marloe - GMT Day

Marloe All Gmt Day Cy Md



Tachymeter bezels are fixed instead of rotating and feature ascending markings going counterclockwise around the outside, usually from 60 to 700. This allows you to convert elapsed time (in seconds) into speed (in units per hour), so you can tell how fast a car, plane, or runner is moving over a fixed distance.

For example, if you’re timing a car, press the chronograph pusher to start the stopwatch when it sets off. When the car passes the finish line, press it again to stop. Check the tachymeter marking next to the second hand and this will tell you the speed of the car. (ie; if it traveled one mile in 40 seconds the tachymeter will read 90 for a speed of 90mph. 

Viqueria - Levante II Chronograph Braveheart

Viqueria Levante Ii Chronograph Braveheart 92ee


A Telemeter bezel is used to determine distance from the wearer to any event which can be seen and heard. For example, to measure your distance from a lightning storm, start the chronograph when you see a lightning flash and stop it when you hear the thunder. You can then read the distance in miles or kilometers on the scale.

Echo Neutra - Hand-wound Chronograph Cortina 1956

Echo Neutra Hand Wound Chronograph Cortina 1956 White Mz Mt


The Yacht-Timer bezel was designed to measure amounts of time while at sea, and sync with race start times during a yachting regatta. It rotates in both directions and has markers from 0-60, with the first 10 minutes marked in 1-minute increments, and the remainder in 10-minute increments.

To calculate elapsed time, rotate the bezel to align the zero marker with the minute hand when the event starts. When it’s over, check where the minute hand is pointing on the bezel, and this tells you how many minutes have passed.

To sync the start of a race, simply align the zero marker on the bezel with the minute hand and use the minute markers to count down to the race start time. It may seem like a pretty niche product, but it can be used to time any event, not just yacht races!

Boldr - Odyssey 45 Regatta

Boldr Odyssey 45 Regatta (black) Ed83


This is a handy little device if you’re out hiking and have lost your actual compass. If you’re in the northern hemisphere, rotate the bezel until the South marker is halfway between the hour and the 12 marker (if you’re in the southern hemisphere do the same, but use the North marker).

Then, keeping the watch horizontal, align the hour hand (or the 12 marker if you’re in the southern hemisphere) with the sun and you can then read off the various cardinal points on the bezel. Reset the bezel once an hour and you should keep going in the right direction.

Norqain - Adventure Neverest 40MM Night Sight

Norqain Adventure Neverest 40 Mm Night Sight 7742


Slide Rule

The Slide Rule is by far the most complicated bezel to use (although it might also be the coolest looking!). It has two mathematical scales, one on the rotating bezel, one on the perimeter of the dial itself, both of them packed with tiny numbers. You can use these to multiply, divide, convert miles to kilometers, calculate air speed or fuel consumption, and who knows what else!

To multiply 12 by 20, for example, you turn the outer bezel until 12 lines up with the number 10 on the inner scale (which is used as the base conversion factor). Then, look for the number 20 on the same inner scale, and read the number underneath (which should, hopefully, be 240).

There isn’t room to go into more complex calculations here (and to be honest they’re beyond us anyway!), but part of the fun of the Slide Rule bezel is learning how to use it yourself.


This is just a basic introduction to the wonderful world of watch bezels. To really get to grips with them you need some hands-on experience, but hopefully we’ve piqued your interest enough to want to find out more!

Created the 2023-05-16

Modified the 2024-03-28

Subscribe to our Newsletter and stay updated!