A laser rangefinder, a GPS watch or a phone can tell you the actual distance to the flag in a round played under the Rules of Golf. What they cannot do is show slope-adjusted yardage, measure the wind, or tell you which club to hit. If your device has those features, you can still carry it. You just cannot use them.
Own a rangefinder with slope? Our slope vs non-slope guide covers the models that let you switch it off, and the rangefinders under $100 page covers the budget end.
The ChartWhat your device may show during a round
| What the device shows | Allowed? | What the rules say |
|---|---|---|
| Actual distance to the flag or a target | Yes | Rule 4.3a(1) allows getting distance or direction information. The USGA lists "Distance between two points (actual)" as fine to access. |
| Scorecard | Yes | Listed by the USGA as fine to access. |
| Tips or advice on playing the hole that were published ahead of time | Yes | The USGA lists "Pre-published information (e.g., swing tips or advice on playing the hole)". Rule 4.3a(3) also allows information gathered before the round. |
| Weather forecast or lightning alert | Yes | The USGA lists local weather information or an alert for nearby lightning. Rule 4.3a(2) allows weather information, wind speed included, that comes from forecasts. |
| Temperature and humidity measured at the course | Yes, per the Rule | Rule 4.3a(2) allows measuring them. The USGA sheet words its ban on measured conditions more broadly, naming wind speed and altitude as examples. If a device shows these, check with the Committee. |
| Wind speed measured at the course | No | Rule 4.3a(2) does not allow measuring wind speed at the course. The USGA lists measured wind speed as off limits. |
| Slope or "plays-like" distance | No | Rule 4.3a(1) does not allow measuring elevation changes. The USGA lists "Displays of effective playing distances (e.g., slope-based and other plays-like distance information)". |
| Elevation or altitude reading | No | Rule 4.3a(1) on elevation changes. The USGA names altitude as an example of a measured condition you cannot access. |
| Club recommendation | No | The USGA lists it as not allowed. Rule 4.3a(1) does not allow interpreting distance or direction information. |
| Recommended line of play | No | Rule 4.3a(1) does not allow interpreting distance or direction information, such as a suggested line of play. |
| Chart of your average club distances from earlier rounds | Yes | The USGA lists a chart of average club distances, obtained from prior rounds, as fine to access. |
| Club distances processed or analyzed from the current round | No | The USGA lists it as not allowed. Rule 4.3a(3) does not allow processing or interpreting playing information from the round. |
| Recording your shots to review after the round | Yes | Rule 4.3a(3) allows recording playing information from the round for use after it. |
| Swing, set-up or other swing mechanics analysis | No | Listed by the USGA as not allowed. |
| Heart rate or other body data recorded during the round | No | Rule 4.3a(3) does not allow using physiological information recorded during the round. The Rule has a separate allowance for equipment used for a medical condition, so ask the Committee if that applies to you. |
Source: The R&A and USGA, The Rules of Golf, Rule 4 (The Player's Equipment); USGA, Understanding the Rules of DMDs.
One thing that surprises people: you are allowed to carry a device that can do the banned things. The Rule is about what you use. The USGA says "access" means you viewed or otherwise used the information, or you used a device where that output is displayed.
Where You Are PlayingCasual round, posted round or tournament
| Round | Actual distance | Slope, measured wind, club advice |
|---|---|---|
| Casual round, not posted | Allowed under Rule 4.3a(1), unless the course has a Local Rule against devices. | Not allowed under Rule 4.3. The sources do not say how a friendly game should treat it, so agree it with your group or ask the pro shop. |
| Posted handicap round | Allowed, unless a Local Rule bans devices. | The round has to be played by the Rules of Golf to count. Rule 2.1b of the Rules of Handicapping says a score is generally not acceptable if a player breaches a Rule without applying the correct penalty, or deliberately ignores a Rule. Not sure about your round? Ask the handicap committee. |
| Club or society competition | Depends on the Local Rules. The Committee may ban devices. | Not allowed under Rule 4.3. If the Local Rules or entry notes say anything different, follow the Committee. |
| U.S. Amateur and U.S. Junior Amateur | Allowed for players and caddies. | Slope function not allowed, per Golf.com. |
| The Open championships | Rangefinders are forbidden, per Golf.com. | Not applicable. |
| Any event using Model Local Rule G-5 | Not allowed. The Local Rule says a player must not obtain distance information by using an electronic distance-measuring device. | Not applicable. |
Source: The R&A, Committee Procedures, Section 8 (Model Local Rule G-5); The R&A and USGA, Rules of Handicapping, Rule 2 (Scores Acceptable for Handicap Purposes); Golf.com, "When and where can you use a rangefinder? A refresher on the rules."
Event notices are where the surprises live. Two tournaments on the same weekend can have different rules, and the Local Rules on the scorecard or notice board win over anything on this page.
PenaltiesWhat a breach costs
First breach: the general penalty. The USGA sheet describes that as loss of hole in match play and two penalty strokes in stroke play.
Second breach: disqualification. The USGA sheet describes it as a second breach of Rule 4.3 during the same round.
A breach of a Local Rule banning devices: the penalty is the one in the Rule 4.3 penalty statement, so it works the same way.
Golf.com reports an LPGA rookie who was disqualified after her caddie used a rangefinder several times, in breach of a Local Rule.
Source: The R&A, The Rules of Golf, Rule 4.3 and Committee Procedures Section 8; USGA, Understanding the Rules of DMDs; Golf.com, "When and where can you use a rangefinder? A refresher on the rules."
In PracticeHow to stay on the right side of it
Check for a device rule before you tee off. Look at the Local Rules on the scorecard, the entry sheet or the notice board. If you cannot find one and you are in a competition, ask the Committee.
Turn the extras off, or hide them. Put slope, wind and club suggestions in the off position before the first tee, and check the indicator on the device. A switch you have to remember mid-round is a switch you can forget.
Watch your wrist. If a device is readily viewable, like a multi-functional watch, and it is displaying information that would be a breach, the USGA says you are considered to have used it, even if you did not look. Set the face to distance only.
Phones need extra care. A phone is a multi-functional device. If a golf app is showing plays-like yardage or club advice on the screen, that counts as access, so set the app up before you start.
Use the allowed extras. The scorecard, a chart of your average club distances from earlier rounds, and a forecast with wind speed are all fine, and you can record your shots to look at later.
Common MistakesWhere people go wrong
"Slope only matters in tournaments." Not quite. Rule 4.3a(1) itself does not allow measuring elevation changes. A Local Rule is what bans distance devices altogether, not what bans slope.
"I own it, so I can't carry it." You can carry it. Rule 4.3 is about how equipment is used, not which equipment you have with you.
"A listing says tournament legal, so I'm covered." That usually describes a switch on the device. Your event's Local Rules decide what applies to you.
Mixing up wind and weather. A forecast that includes wind speed is allowed. Measuring the wind at the course is not. Temperature and humidity are allowed by the Rule, though the USGA sheet's wording is broader, so ask if your device shows them.
Anything these sources do not answer, such as a custom device, a new feature or a house rule at your club, is a question for the Committee or the pro shop.
FAQQuick answers
Can I use a rangefinder in a handicap round?
For actual distance, yes, unless the course has a Local Rule banning devices. The round still has to be played by the Rules of Golf to be acceptable for handicap purposes, which is Rule 2.1b of the Rules of Handicapping.
Is slope allowed on a rangefinder?
Not in a round played under the Rules of Golf. Rule 4.3a(1) does not allow measuring elevation changes, and the USGA lists slope-based distances as something you cannot access. Golf.com reports the same in the U.S. Amateur and U.S. Junior Amateur, where rangefinders are allowed without the slope function.
Am I breaking the rules just by carrying a rangefinder with slope?
No. Rule 4.3a allows you to carry a device that can do prohibited things as long as you do not use those functions. The USGA says the same: it is the access that counts.
Can I wear a GPS watch?
Yes. The USGA lists watch-style GPS units as stand-alone devices. The catch is the screen: if the watch is displaying something that would be a breach, you are considered to have used it, whether or not you looked.
What is the penalty for using a banned feature?
The first breach is the general penalty, which the USGA describes as loss of hole in match play or two penalty strokes in stroke play. A second breach is disqualification.
Can I check the wind on my phone?
A weather forecast, including wind speed, is allowed under Rule 4.3a(2). Measuring the wind at the course is not. If your phone has an app that does the second, keep it closed during the round.