Take a walk down a practice putting green on tour, or indeed at many top amateur tournaments, and you’ll might see a host of players going through their drills accompanied by a little box. While it doesn’t look like the kind of tool you’d see a carpenter or a bricklayer toting, it is a spirit level and golfers use them to measure slope on a green and gauge the contours.
Now you might ask, do golfers really need to use spirit levels? Some top players and coaches swear by them, but if you’re thinking of getting stuck into a new trend will it get you into bother with the Rules of Golf?
Can you measure slope on a green, and what else do you need to watch out for if you’re trying to figure out a many layered putting green? Let’s take a look…
Can you measure slope on a green? Restrictions on using equipment

You can use a compass. Did you know that? You can get information on distance or direction from a range finder, watch, or other distance measuring device (unless there’s a Local Rule in place preventing this).
But Rule 4.3a (1) prevents you from doing anything that measures elevation changes, using an alignment device to help align the ball, or using a device that would give you a recommended line of play or help you with club selection based on where your ball is positioned.
A clarification to this rule reveals that you can use your club as a plumb line to help you work out the slope, but that’s where the leniency ends.
You can’t hold or place a “bubble level”, you can’t use a weight suspended on a string to act as a plumb line (have you ever actually seen anyone do that?), and, probably more pertinently for amateurs like us, you can’t place a bottled drink to act as a level.
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You might have missed it on the PGA Tour in all the furore about restricting green books in late 2021, but they went further still – setting down new tournament regulations that banned the use of any device that could test the condition of practice greens as well as their use in practice rounds or pro-ams.
But what will happen to you in a competition round if you’re using your bottle of pop to somehow measure slope on a green at your club?
It’s a savage penalty – two shots in stroke play or loss of hole in match play for the first offence and disqualification if you do it again.
Got a question for our expert?
Despite the changes to the Rules of Golf in 2019 and 2023, there are still some that leave us scratching our heads. I’ll try to help by featuring the best of your queries in this column.
Have you ever tried to measure slope on a green? Let me know by leaving a comment on X.
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