MOI Matching

After my last blog post, I had some golfers ask me about ‘MOI Matching.’

First, we should know that MOI stands for ‘Moment of Inertia.’ Secondly, there is essentially 2 different types of weight matching with golf clubs…MOI matching and ‘swingweight matching.’

I would estimate that 99% of golfers have clubs that are swingweight matched. In fact, many golfers have clubs where the manufacturer or clubmaker tries to do a poor man’s version of MOI matching. But, I will get to that in a moment.

The main idea is to get each club to feel the same when we swing it. With swingweight matching, we put the club on a swingweight scale and if we want the swingweight at D-3 for a 3-iron, then we want it at D-3 with our 9-iron. Where some OEM’s and clubmakers do a ‘poor man’s version of MOI matching’ is that they will slightly increase the swingweight the shorter the club gets. Thus, a 3-iron may have a D-2 swingweight, but the golfer’s 9-iron may have a D-4 swingweight. More on that in a bit.

As Tom Wishon says on his Web site, MOI matching in its simplest form is scientifically making each club require the same amount of effort to swing.

Now, I’m still learning about MOI matching, but the main difference I see is that with swingweight matching, one can have two clubs that are the same length, but the weights can be completely different. One head can weigh more, one shaft can weigh less, the balance point of the shaft can be different, the weight up towards the grip end can be different…and yet, still manage to have the same swingweight. The problem is these two clubs can swing nothing alike.

For instance, ever have one club in your bag that feels lousy compared to the rest? This happens with me as there is a distinct difference in how my Wishon 555C 3-iron feels from my Wishon 555C 4-iron. I hit the 4-iron fantastic, but the 3-iron feels off to me every time I hit it. I can hit some great shots with it, but not with much consistency. But, they have the same exact swingweight. My philosophy is that the MOI is likely very different.

And that’s where I hope to have MOI matching come into play.


There are a few different ways to determine what the best MOI is for each golfer, but it’s based on actual results. One way some clubfitters MOI match is to ask the golfer what their favorite club is in the bag, measure the MOI on a MOI frequency machine (pictured above) and then strategically place weights (not lead tape) in the club to get the MOI to match that favorite club of the golfer. Again, that’s one way a clubfitter can find the best MOI, there are other methods as well.

What will happen when the clubs are MOI matched is that the swingweight will actually get heavier as the clubs get shorter. So, you may have a perfect MOI match throughout your set of irons, but the 3-iron may be at a D-2 swingweight and the PW may be at a D-6 swingweight. However, the clubs will take the same amount of force to swing.

The reason why I say some OEM’s and clubmakers use a ‘poor man’s MOI matching’ is that they more or less blindly add more swingweight as the clubs get long, but that does not mean that they are MOI matched.

I plan on getting to this in the next month or so and I will be offering this service, at a fee, for those who are interested.






3JACK