How do golf GPS watches work?

Step 1: finding your position

The watch has a receiver that listens for signals from navigation satellites. GPS is the American system; many watches also use others such as Galileo (European) and GLONASS (Russian), which gives more satellites to work with. By timing signals from several satellites, the watch calculates its latitude and longitude.

Getting the first fix can take a little longer when you start a round, especially if the watch has not been used for a while or you have travelled. Starting the golf app in the car park, before you reach the first tee, gives it time.

Step 2: the course map

The watch also holds a map of each course. Makers survey or map courses and mark points such as the front, middle and back of every green, bunkers, water, doglegs and layup points. Watches with full hole maps hold a more detailed outline of each hole. Many come with tens of thousands of courses preloaded; the Garmin Approach S44 listing says 43,000+ and the Shot Scope G6 listing 36,000+.

Map quality matters as much as the GPS. If a green has been rebuilt or a tee moved, the watch will be out until the map is updated. That is why makers release course updates through their apps or software; see how to update Garmin golf courses.

Step 3: calculating the yardage

With your position and the map points, the watch calculates the straight line distance to each point and shows it in yards or metres. As you walk, it updates. Most watches detect which hole you are on from your position and move to the next hole automatically.

Some watches can also show plays like distances that adjust for elevation using height data in the map. Those must be turned off in competition under Rule 4.3 of the Rules of Golf, published by The R&A.

Does a golf GPS watch need internet or a phone?

No, not on the course. GPS signals come from satellites and need no mobile signal or internet. Once the course maps are on the watch, it works on its own. You will usually need a phone app or computer to set the watch up, update courses and software and view stats after the round. Some watches link to a phone during the round for extra features, such as notifications, but distances do not depend on it.

What affects accuracy

Consumer GPS is usually accurate to within a few metres in open sky, and golf courses are mostly open sky. Accuracy can drop near tall trees, buildings or steep banks that block part of the sky, and in the first moments after starting. Map errors are the other main cause of wrong yardages.

GPS against a laser

A watch gives distances to fixed points on the green; a laser gives a distance to the flag, wherever it is cut. That is why the two can differ by several yards on a deep green. Many golfers use both: GPS for the front and back and hazards, laser for the pin. Read golf GPS watch vs rangefinder and how golf rangefinders work.

Compare golf GPS watches →

Which is most accurate?

Because all reputable watches use similar satellite receivers, differences come mostly from map quality, update frequency and how quickly the watch gets a fix. Brands that map courses carefully and update often tend to give the most dependable numbers. Our golf GPS watch features explained covers the features that matter.

Frequently asked questions

Does golf GPS work without a phone signal? Yes. It uses satellite signals and maps stored on the watch.

How accurate is a golf GPS watch? Usually within a few yards in open sky, depending on the map and the satellite fix.

Why does my watch show a different number from my laser? The watch measures to fixed points on the green; the laser measures to the flag.