# What is a GMT watch and how to use one Source: https://lumeandbezel.com/blog/how-to-use-a-gmt-watch Published: 2026-10-09 Publisher: Lume & Bezel **Short answer:** A GMT watch adds a fourth hand that goes around the dial once every 24 hours, read against a 24-hour scale on the bezel or dial. Set it to your home time, then set the main hands to local time. Turning the 24-hour bezel lets you read a third time zone from the same hand. GMT watches are made for travelers, remote workers and anyone who calls people in other time zones. This page explains what a GMT watch shows, the difference between a traveler's GMT and a caller's GMT, how to set one in the right order, and how to use the bezel to track a third zone. It applies to automatic GMT models like the Seiko 5 Sports SSK001, Orient Mako GMT and Bulova Oceanographer GMT. ## What a GMT watch shows GMT stands for Greenwich Mean Time, the old reference time for the world. A GMT watch has the normal hour, minute and seconds hands plus a 24-hour hand, often in a contrasting color with an arrow tip. The 24-hour hand makes one turn per day, so it can show whether it is 9 am or 9 pm in the other zone. The 24-hour scale is usually on a rotating bezel, as on the Seiko SSK001 and Orient Mako GMT, or printed on the dial or a fixed bezel on some dressier models. Two time zones are read from the hands; a third is possible by rotating the bezel. ## Traveler GMT vs caller GMT There are two common designs. In a **traveler** or true GMT, the main hour hand jumps in one-hour steps on its own while the watch keeps running. You land, pull the crown, jump the hour hand to local time, and the 24-hour hand stays on home time. The Bulova Oceanographer GMT listing describes this as an independently adjusted hour hand for local time. In a **caller** or office GMT, the 24-hour hand is the one that moves on its own. The main hour hand only moves together with the minute hand. This suits people who stay home and track a second zone for calls. Many affordable automatic GMTs work this way. Check your manual to see which kind you have; the setting order below covers both. ## How to set a GMT watch 1. Wind the watch or make sure it is running. 2. Pull the crown to the time-setting position (usually the last click). Set the main hour and minute hands to your home time, watching the 24-hour hand so it points to the correct home hour on the 24-hour scale (for example 14 for 2 pm). 3. Push the crown in to the middle position. On a traveler GMT, turn it to jump the main hour hand to local time. On a caller GMT, turn it to move the 24-hour hand to the second zone's time. 4. Set the date in the same middle position if your watch has one. On many GMTs the date follows the local hour hand. 5. Rotate the bezel so 24 or the triangle is at the top when you want the 24-hour hand to read directly against the dial's own hour time. 6. Push the crown in and screw it down if it is a screw-down crown. Note: As with any date watch, avoid changing the date while the hands are between about 9 pm and 3 am unless your manual says it is safe. See [how to set an automatic watch](https://lumeandbezel.com/blog/how-to-set-an-automatic-watch). ## Reading a third time zone with the bezel Once home time is on the 24-hour hand with the bezel at zero, you can add a third zone without touching the crown. Count the time difference in hours between the zone the 24-hour hand shows and the third zone. Rotate the bezel until the number under the 24-hour hand has changed by that many hours: a higher number if the third zone is ahead, a lower number if it is behind. Now read the 24-hour hand against the rotated bezel for the third zone. Rotate back to zero to return to the original reading. Example: the 24-hour hand is on New York time and you want London, which is usually five hours ahead. Turn the bezel so the 24-hour hand points five hours later on the scale. When the 24-hour hand reads 14 against the fixed position, the bezel reads 19 for London. ## Dive watch with GMT: what to know Some GMT watches, like the Orient Mako GMT with 200 m water resistance per its listing, have a dive-style case but a 24-hour bezel instead of a 60-minute timing bezel. That means you lose the elapsed-minute bezel used for diving. If you need both, look for a model with a separate 24-hour scale on the dial. See [how to use a dive watch bezel](https://lumeandbezel.com/blog/how-to-use-a-dive-watch-bezel) for the timing bezel. ## Choosing a GMT watch - Traveler GMT if you fly often and want local time on the main hands. - Caller GMT if you mostly stay home and track a colleague's zone. - Bidirectional 24-hour bezel if you plan to use the third-zone trick often. - Legibility: a bright, distinct 24-hour hand is easier to read at a glance. - Size: GMT cases are often larger, so check lug to lug against your wrist. [See the best GMT watches under $1,000](https://lumeandbezel.com/best/best-gmt-watches-under-1000) ## Frequently asked questions **What does GMT mean on a watch?** It refers to Greenwich Mean Time and means the watch has a 24-hour hand for tracking a second time zone. **Is the Seiko SSK001 a true GMT?** The SSK001 uses Seiko's 4R34 caliber, where the crown adjusts the 24-hour hand independently. That is generally described as a caller-style GMT. Check Seiko's manual for your reference. **Can a GMT watch show three time zones?** Yes. The main hands show one zone, the 24-hour hand shows a second, and rotating the 24-hour bezel lets the same hand show a third. **Do I need a GMT watch for travel?** Not strictly, but it saves mental math and lets you check home time at a glance without unlocking your phone. ## Gear guides for this topic - https://lumeandbezel.com/best/best-gmt-watches-under-1000 - https://lumeandbezel.com/best/best-seiko-5-sports-watches - https://lumeandbezel.com/best/best-orient-automatic-watches