Can a lined ball or a mallet do your aiming for you?
One study found the number of lines on the ball changed nothing about how accurately golfers aimed it. The 0.9% belongs to a simulated design nobody built.
I asked in a shop why my putts leak right. The answer was that a mallet is better for direction. I already putt with one, and it has a line printed on the top. I don’t use that line.
What I wanted to know was whether any of that hardware does the aiming for me. So I went looking for measurements. There are fewer than you’d expect, and both of the ones I found come with a warning label.
The short answer
- In the one study that measured it, the number of lines on the ball changed nothing about how accurately golfers aimed it. Three lines on the putter did improve how accurately it was aimed.
- That study is 43 people in a journal PubMed doesn’t index. It’s a reason to test your own aim, not a finding to lean on.
- A mallet’s forgiveness is about mishits. It does nothing for a centered strike with the face open.
- The 0.9% best case belongs to a simulated design that adds a 4 mm flexible face to perimeter weighting. Nobody built it.
Does the line on the ball help you aim?
Not the number of lines, in the one study I could find that measured it.
Researchers compared balls and putters carrying one aiming line against three, with 43 golfers, from about 5 and 10 feet (1.5 and 3 meters). The accuracy of ball alignment didn’t change with the number of lines. It didn’t change with the golfer’s experience either.
Aiming the putter itself did improve with three lines. The predicted success rate and how satisfied people felt went up too, with three-line balls and putters used together (Kim and others, Medical Hypothesis, Discovery and Innovation in Optometry, doi 10.51329/mehdioptometry124, 2021, retrieved 2026-09-09).
You can’t lean on this one hard. It’s 43 people in a small journal that PubMed doesn’t index. You’ll want to take it as a reason to test your own aim rather than trust it.
For what it’s worth, my Scotty Cameron Phantom X 5 has a line and I don’t use it. I look at the middle of the ball. I’ve never checked whether that helps me, which is exactly what I’m saying you should check.
A mallet’s forgiveness is about mishits, not aim
MOI, or moment of inertia, is how much a head resists twisting when you miss the middle. That is the whole claim behind a big head, and it is a claim about mishits.
One study simulated three putter bodies that all weighed 350 grams and carried the same 5 mm face. One was a blade shape, one had mass in the center, one had mass at the perimeter. The perimeter-weighted body left the least variation in roll distance across the face. The blade showed much greater variation.
The authors put a percentage only on their proposed design, which adds a 4 mm flexible face on top of the perimeter weighting. That combination varied as little as 0.9% in roll distance between a centered strike and one 20 mm (0.8 in) out. The standard bladed putter they compared it against, with its fixed face, varied 7.2% across the same range (Emerson, Morris and Potts, MDPI Proceedings, a conference paper, 2018, retrieved 2026-09-09).
Read that for what it is. The face test was physical, the body comparison was computer simulation, and the authors write that there is no combined prototype at this stage. The author list includes a Ping Europe affiliation.
A separate robot test used nine putter designs: three blades, three mallets, and three high-MOI heads. It found that “not every high MOI putter necessarily performs better than a blade putter on an off centre hit” (Paul Hurrion, 2018, retrieved 2026-09-09).
The simulation and the robot test don’t land in the same place. Both findings are about the same thing: strikes away from the middle of the face. If you catch the ball in the middle and the face is open, a higher MOI does nothing for you. A bigger head can’t aim.
So should you buy either?
Not as your first move. Both are answers to questions you haven’t measured on yourself yet.
Start by finding out whether you’re missing the middle of the face at all. Impact tape, or a little foot spray on the face, will show you in ten putts. I haven’t done that yet either.
If you’re not missing it, the mallet has nothing to give you. What’s left is aim or face angle, and a bigger head doesn’t touch either one.
Face angle is where the face points at the moment it meets the ball. It decides most of where a putt starts, and that’s the subject of what actually decides where a putt starts.
If you’re missing the middle, the simulation says perimeter weighting helps. The robot test says it doesn’t always show up in real heads. If it were me, I’d take the robot test, because it hit real putters.
The line on your putter is cheaper to test than either one. Aim it at your target and set up. Then let the putter go and step back without touching it, and see where the face points. Then do it again without using it.
A putter’s torque and balance are separate properties from MOI. I wrote about that in what a zero-torque putter would cost me.
Where I’ve got to
I still leak right, and I still don’t use the line on my putter. I haven’t tested either of these on myself, and I won’t claim a result I don’t have.
The honest state of it is thin. One small study says the number of lines on the ball didn’t change how accurately golfers aimed it. One simulation says a perimeter-weighted head helps a mishit. Neither is a reason to buy anything today.
Terms in this article
- MOI, or moment of inertia - how much a head resists twisting when you hit it off center. Bigger heads with mass pushed toward the edges have more of it.
- Perimeter weighting - putting the head’s mass out at its edges instead of behind the middle of the face. This is what raises MOI.
- Face angle - where the putter face points at the moment it meets the ball, measured against your target line. Open means pointing right of it for a right-handed player.
- Alignment line - a printed or milled line on the top of a putter, or on the ball, meant to show you where you are aimed.