Are rangefinders and GPS watches legal in golf?

What Rule 4.3 says about distance devices

Rule 4.3 covers the use of equipment during a round. It allows a player to get information on distance or direction, for example from a laser rangefinder, a GPS watch, a handheld GPS unit or a phone app that shows yardages. This has been the default position in the Rules of Golf since the 2019 rewrite. Before then, distance measuring devices were only allowed if a Local Rule permitted them. The change means that, unless your club or the event says otherwise, you can laser the flag or glance at your watch for the front of the green in a stroke play medal.

What Rule 4.3 does not allow is using a device to measure elevation changes, or to interpret distance or direction information in a way that gives advice, such as a device that recommends a club based on where your ball lies. Measuring conditions such as wind speed is also not allowed. In practice that means the slope function on a laser and the 'plays like' numbers on a GPS watch must not be used during a round played under the Rules.

• Allowed by default: straight line distance to the flag, a bunker, a tree or any other target.
• Allowed by default: GPS distances to the front, middle and back of the green and to hazards.
• Not allowed in a round: slope or elevation adjusted distances.
• Not allowed in a round: features that measure wind or recommend clubs or lines of play.

Compare distance-only and slope rangefinders →

When a Local Rule can ban them

The Rules give the Committee running a competition the power to change the default with a Local Rule. The R&A's Model Local Rule G-5 lets a Committee prohibit the use of distance measuring devices altogether. Some events and some clubs choose to do this, and elite amateur or professional events set their own conditions. If a Local Rule bans the devices, using one during the round is a breach even if it only shows straight distance.

For most UK club golf, devices are allowed and no Local Rule bans them. Even so, it is worth checking the competition terms on the notice board or the booking app before a medal, an open or a county event, especially if you play away from your home club. If you are not sure, ask the Committee or the professional's shop before you tee off rather than after the card is signed.

Slope devices: switch the function off

A device that has a slope function is not banned in itself. You may carry and use a slope laser in competition provided the elevation feature is turned off and you use it only for distance. This is why makers fit external slope switches, coloured faceplates or a clear 'slope off' indicator in the display: it lets you and your playing partners see that the device is in its legal mode. Some models change mode through a button or menu instead, which works just as well under the Rules but is less obvious to a marker.

The Rules also set penalties for using a device in breach of Rule 4.3, and a repeat breach in the same round can lead to disqualification. The exact wording is on The R&A's Rule 4 page, linked in the sources below. The practical habit to build is simple: set the device to distance only before the first tee in any competition, and do not switch slope back on until the card is in.

1. 1

   Before a competition round, check the notice board or app for a Local Rule on distance devices.

2. 2

   Switch slope or plays-like distance off, using the external switch or the menu, and check the display.

3. 3

   On a watch, turn off any PlaysLike or slope distance setting if your model has one.

4. 4

   Leave the setting off until you have signed and returned your card.

Note:The Rules of Golf are written and updated by The R&A and USGA. This article is a plain English summary, not an official interpretation. Your Committee's decision on any question is final.

See slope lasers with a clear on/off control →

GPS watches, phone apps and other devices

The same principles apply to GPS. Front, middle and back distances, hazard carries, layup numbers and the green shape are distance and direction information, so they are allowed by default. Features that adjust distances for elevation must be turned off. Some watches also offer club recommendations, green undulation arrows or virtual caddie advice; check each feature against Rule 4.3 and switch off anything that interprets information for you rather than just measuring it.

Phones are allowed for distance apps under the same conditions, and you can use a phone for other purposes such as checking the weather, but listening to swing advice or using an app that analyses your swing during the round is a different question under Rule 4.3. When in doubt, use the device for distance and nothing else during a competition.

Practice rounds and casual golf

In a practice round, a bounce game or a lesson, nothing stops you using slope. Many golfers find it useful to see how much a raised green adds or a downhill par 3 takes off, and it teaches you to judge elevation by eye. If you want to understand the maths behind those numbers, our slope explainer and the rangefinder maths tool show how line of sight distance, angle and height relate.

For general play scores you submit for handicap, the safest approach is to play under the Rules as you would in a competition and keep slope off. If your device has a slope function you will use most weeks, choose one where the switch is quick and obvious. Our slope rangefinder guide compares how each model handles it.

Frequently asked questions

Can I use a laser rangefinder in a club medal? Yes, unless the Committee has made a Local Rule banning distance devices. Slope must be switched off and you may only use the device for distance and direction.

Is a rangefinder with slope illegal? No. A slope laser can be used in competition as long as the slope function is turned off. Using the slope reading during the round is a breach of Rule 4.3.

Are GPS watches allowed in competitions? Yes, under the same rule. Distances to the green and hazards are allowed, but plays-like or elevation adjusted figures and club advice features must not be used.

Where can I read the exact wording? Rule 4 of the Rules of Golf on The R&A website sets out what equipment is allowed, and the Committee Procedures section includes the Model Local Rules.