I have never been a big fan of the stat Putts Per Round because it doesn’t really tell you much information about the player’s performance. For example, you could hit 18 greens and have 36 putts and shoot par, or hit zero greens have 18 putts and shoot par. So the stat is highly dependent on the number of greens in regulation (GIR) and approach shot proximity.
This is one of the reasons Strokes Gained Putting was invented, to shine a light on pure putting performance compared to the field given the length of the putt, but it still doesn’t give you a total picture of approach shot performance. For example, if the player hit 18 greens but no closer than 30 feet, he could two putt all of them and shoot even par and be positive Strokes Gained Putting. But if he hit 18 greens to 10 feet and made 6 birdies, he would be negative Strokes Gained Putting, even though it is clearly the better of the two rounds.
Today a student asked me what would be considered a good ratio of Greens in Regulation to Putts Per Round, so let’s dissect it a little bit. A tour player should have the goal of 1.70 putts per green in regulation, which equates to a 30% birdie conversion. But if they miss the green the goal for scrambling should be 75%, or a putts per missed-green of 1.25. Making an equation out of that gives us:
(1.70*GIR) + (1.25*Missed GIR) = Target Putts Per Round
Simplifying we get:
(1.70*GIR) + (1.25*(18-GIR) ) = Target Putts Per Round
or
1.70GIR + 22.5 – 1.25GIR = Target Putts Per Round
which finally is equal to:
0.45GIR + 22.5 = Target Putts Per Round
Plugging that into your round of golf, if you hit 11 greens your target Putts Per Round number is (.045*11) + 22.5 = 27.5. If you hit 9 greens it’s 26.5 putts. And if you manage to hit all 18 greens in regulation, a great putting number would be 30.6.
We still don’t have a good representation of approach shot proximity, but if you want a quick formula for “Did I putt well or not” and you don’t have access to Putts Gained data, this is a good proxy. You should always dig deeper into performance if not hitting your goals and separate GIR putts from scrambling putts to see where the weakness is as well. And if you want a formula that is a little easier to figure out on the fly, just use 0.5GIR + 22.5. 22.5 is the baseline that never changes and then just add that to half of your GIR number.
