Club Mass Properties & Performance: What Every Fitter Should Know

By Philip Dye

Introduction

When it comes to golf club fitting, many players and custom fit specialists focus heavily on factors like loft, lie angle, and shaft flex. While those are undeniably important, there’s another category of variables that can also impact performance which are often overlooked: weight, and swing-weight. Understanding how the total mass, and swing-weight affect performance can help players find a setup that not only fits their physical ability but also supports more consistent performance.

Drawing on insights from the PING, Callaway and several research-backed resources that blends theory with real-world fitting experience, this article explores how the total mass and swing-weight work independently and together, and what their practical implications are for both golfers and fitters.

Total Mass

Total mass refers to the overall weight of the golf club and is measured in grams. This includes the head, shaft, grip, and any additional weight elements. Typically, a heavier club feels more demanding to swing, while a lighter club can allow for fasters swing speeds (Cochran & Stobbs, 1968).

The total mass of a golf club is primarily made up of three components:

Grip weight (typically 45–60g)
Shaft weight (can range from 40g in ultralight graphite to 130g in heavy steel)
Clubhead weight (approximately 190–205g for drivers and 250–280g for irons)

Adjustments to any of these components will affect the club’s total weight and, potentially, its overall swing dynamics.

Swing-Weight

Swing-weight is a measurement of how the club’s mass is distributed, specifically, how heavy the club ‘feels’ when it is swung. It’s represented on a scale ranging from A0 (lightest) to G9 (heaviest), with most standard clubs falling between C5 and D5. Unlike total mass, swing-weight doesn’t necessarily change if you add weight to both the grip and the head. It’s all about balance and feel.

A Brief History of Swing Weight

The concept of swing-weight dates to the early 20th century as club manufacturers sought to quantify the 'feel' of a golf club. Originally, swing-weight was measured using a simple balance scale, where the club was balanced on a fulcrum and the weight of the grip end was compared against a known reference. This early method laid the groundwork for the modern swing-weight scale, developed by Robert Adams in the 1930s (Tutelman, ND).

Two primary systems for measuring swing weight were experimented with:

The Lorythmic Scale: This scale was used to mathematically calculate the relationship between clubhead weight and shaft length by using a logarithmic formula to determine the moment of force. It considered both the length of the club and the position of the weight to calculate a swing feel coefficient. The intent was to provide a more precise way of comparing clubs based on their moment characteristics. However, the system required log tables and more complex math, making it impractical for everyday use by clubmakers or fitters. As a result, it never gained mainstream adoption.
The Lever Balance Scale (Modern Swing-Weight Scale): This is a simpler, more user-friendly system that measures the torque required to balance the club on a fulcrum 14 inches from the grip end. This is the method still used today, expressed in alphanumeric values such as D1 or D2. Swing-weight has become a widely accepted standard because it gives clubmakers and fitters a repeatable way to match club feel across a full set of irons or between different builds.

Modern Swing-Weight Scale: Image courtesy of Glazer, 2022

Individual Component Contributions to Swing-Weight

While swing-weight is a useful measure of club feel, it's important to understand how different parts of the club contribute to it. Each component, the grip, shaft, and clubhead affect swing-weight based on two factors: its mass and its distance from the fulcrum point of the swing-weight scale.

The standard formula used to calculate the contribution of each component is:

CG (inches) × Weight (grams)

Where:

CG represents the centre of gravity of the component, measured in inches from the pivot point (which is fixed at 14 inches from the butt end of the club).
Weight is the component’s mass in grams.

This calculation highlights that, components further from the fulcrum (such as the clubhead) have a disproportionately large impact on swing weight compared to those closer (like the grip). For example, adding 2 grams to the clubhead significantly increases swing weight, while adding the same amount to the grip has a much smaller and lightening effect.

What does the grip contribute to swing-weight?

Let’s use an example to illustrate the contribution of the grip to swing-weight. If we take the CG of the grip to be 10 inches from the swing-weight fulcrum and assume a grip weight of 55 grams we get the following:

-10" x 55 = -550inlgrams.

(550/50) = 11

*50inlgrams is equivalent to 1 Swing-weight

The result is that the addition of the grip will reduce the swing-weight by 11 swing weight points.

Now let’s have a look at another example, but this time let's look at the effect on swing-weight when increasing clubhead weight on two clubs that are different lengths. Swing-weight is relative to the constant fulcrum and so the length of the golf club is important.

Example:

Let’s assume a club length of 37” and a head weight of 285g where the clubhead CG is 23” from the fulcrum. We can use the previous formula to help calculate the amount of change in swing-weight when 2 grams added to the clubhead.

2 grams x 23"= 46inlgrams

46/50 = 0.92 swing-weight points

The result is that the addition of 2 grams increases the swing-weight by 0.92.

Now let’s look at a longer club. Assuming the driver is 45” and has a clubhead weight of 200g:

45 - 14 = 31

2 grams x 31" = 62 inlgrams

62/50 = 1.24 swing-weight points.

In these examples we can see that for the 37” club, a 2 gram increase in the head weight increased the swing-weight by 0.92 however, for the longer club, the same change in head weight resulted in a swing-weight increase of 1.24. What is important to take away from this is that for longer clubs, smaller changes in head weights are required to meaningfully impact the clubs swing-weight.

How does club length affect swing-weight?

Before moving on to the shaft, lets stay with length for a moment and see what happens to the swing-weight when we alter club length. Let’s assume a combined driver head and shaft weight of 250 grams with a club length of 46”. To calculate the change in swing-weight for an increase in club length of 1" we convert the combined weight into inlgrams and then divide by 50 to find the swing-weight change

250*1=250 inlgrams

250/50 = 5 swing-weight points

The result, increasing the club length by 1” will add 5 swing-weight points to the driver.

Now for an iron:

Again, we need some data. Let’s assume a combined clubhead and shaft weight of 350g and a club length of 37":

350*1 = 350 inlgrams

350/50 = 7 swing-weight points.

The result, increasing the club length by 1” will add 7 swing-weight points to the club. What is important to take away from these examples is that shorter clubs are impacted more by changes in club length, and it is often these clubs such as wedges and putters that are tinkered with the most.

How can we accommodate changes in club length?

When club length is adjusted, it is possible to maintain the same swing-weight by compensating with changes to head weight. This allows fitters to fine-tune performance without sacrificing the club’s feel.

Returning to our driver example, we saw that adding 1" increased the swing-weight by 5 swing-weight points. To reduce this, we would need to change the head weight by 7.8 grams:

250 inlgrams /32" = 7.8.

For the iron we would need to reduce the head weight by 15.2 grams!!

350 inlgrams /23" = 15.2g

These examples highlight how club length has a substantial effect on swing-weight especially in shorter clubs like irons, wedges, and putters. A 1-inch increase in length results in a more significant swing-weight increase in shorter clubs due to the reduced distance between the added mass and the fulcrum. While it is theoretically possible to offset these changes by reducing head weight, doing so is often impractical particularly in irons, where the head design, structural integrity, and manufacturing constraints limit how much weight can realistically be removed. This underlines the importance of considering length adjustments carefully during a fitting and reinforces the need for a strategic approach when matching swing-weight across a set.

How does the shaft contribute to swing-weight?

Finally, let’s look at the shafts contribution to swing-weight. This is calculated by taking the shaft weight and multiplying it by the shafts CG position relative to the fulcrum as in previous examples:

Shaft-weight x Shaft CG relative to the fulcrum = Swing-weight contribution

Example:

Shaft 1: Mitsubishi Kai'li White 70

79.1g x (21.8(CG position) -14) = 616.98 inlgrams

616.98/50 = 12.3 swing-weight points.

Shaft 2:Mitsubishi Kai'li White 60

67.8g x (22.3(CG position) -14) = 562.74 inlgrams

562.74/50 = 11.25

From these examples we can see that the first shafts contribution to swing-weight is 1.05 swing-weight points more than the second.

So how does swing-weight affect performance?

To better understand the real-world effect of club mass properties, PING engineers conducted a controlled study using three different drivers with different total masses (396g, 444g, and 494g) while keeping the swing-weight constant (D3.9) and shaft length fixed at 45.25”.

Seventeen mixed-handicap golfers participated, each hitting eight drives with each club and performance data was collected using a launch monitor and motion capture systems. The test showed that while there was a significant difference in total mass between the three test clubs, the impact on club head speed was minimal with only a 0.6mph difference in club head speed across all clubs (97.8mph, 97.3mph, and 97.2mph). They also reported that differences in the face angle at impact were insignificant, ranging from +0.5° to 1.2° respectively.

A second test revealed more significant findings. 18 golfers used three clubs with different total weights and increases in head weight were used to change the swing-weight from C7.4 in the lightest club, D4.2 in the second and D9.3 in the heaviest variation. The results revealed that the change in head weight, and resultant swing-weight, resulted in a 2.5mph change in club head speed. The lightest club producing 107.6mph, the second 106mph and the heaviest of the three producing an average of 105.1mph.

Again, when it came to the face angle measurements, as the club became heavier, the face angle position at impact became more open but this time the difference was more meaningful going from closed in with the lightest club (174g, -0.10) to 1.6° open with the heaviest (190g +0.7°: 200g +1.6°).

Key takeaways from the tests are that adding weight to the clubhead:

· has a 10X influence on clubhead speed relative to adding weight to the grip and shaft.

· can have a 6X influence on the face angle relative to adding weight to the grip and shaft

Final thoughts

This article has explored several factors impacting the clubs total mass and swing-weight and how each contributes to the feel and performance of the golf club. Through examples, formulas, and PING’s test data, we've seen how even subtle changes in weight distribution can influence delivery focusing on clubhead speed and face angle at impact.

While findings from Choi et al. (2024) and others support the idea that shaft and head weight changes can affect swing speed and feel, it’s worth noting that Wallace and Grimshaw (2005) found that changes in weight distribution, when measured using swing-weight alone, had minimal effect on player performance and in their study, most golfers were unable to reliably perceive small variations in swing weight.

This contrast underscores a key takeaway for fitters: the technical elements of club design and balance must always be weighed alongside player feedback, ball flight data, and individual preferences. Some players may benefit greatly from precise adjustments, while others may not perceive or respond to small changes at all.

As we’ve discussed in previous blog posts, effective fitting isn't just about knowing the specs, it’s about knowing the player. A holistic approach that combines measurement with experience, and data with dialogue, is essential to delivering better golf club performance.

References

Choi, A., Jung, S., Kim, S. and Kim, J., 2024. The effects of different iron shaft weights on golf swing performance. Journal of Exercise Rehabilitation, [online] 20(1), pp.32–40. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10877370/ [Accessed 7 Apr. 2025].

Cochran, A.J. and Stobbs, J. (1968) The Search for the Perfect Swing. Philadelphia: J.B. Lippincott Company.

Cross, R., 2009. Effects of swing-weight on swing speed and racket power. University of Sydney. Available at: https://www.physics.usyd.edu.au/~cross/PUBLICATIONS/33.%20SwingSpeedvsSW.pdf [Accessed 7 Apr. 2025].

Tutelman, D. (2008) 'Heft of the club: Swingweight & MOI'. Available at: https://www.tutelman.com/golf/design/swingwt1.php#swScale (Accessed: 8 April 2025).

Wallace, E.S. and Grimshaw, P.N., 2005. Driver swingweighting: A worthwhile process? Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 219(3), pp.161–165. Available at: https://journals.sagepub.com/doi/10.1243/095440505X32247 [Accessed 7 Apr. 2025].

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