Shaft flex is one of the first specs golfers look at when buying a new shaft, but the letter on the label only tells part of the story. This guide explains what flex is, how it relates to swing speed and tempo, and the signs your current flex may not suit you.
What is shaft flex?
Flex refers to the amount of bend, or stiffness, in a golf shaft. A softer shaft bends more during the swing and a stiffer shaft bends less. Shaft makers such as True Temper list swing speed, tempo, ball flight and feel preference as factors that all influence the ideal shaft.
The common flex letters
Most shafts are labelled with a letter. From most flexible to stiffest, the usual range is:
- L: Ladies, the least stiff.
- A: often called Senior.
- R: Regular.
- S: Stiff.
- X: Extra Stiff.
- TX: the stiffest option, used by some makers.
Some brands use their own codes. UST Mamiya, for example, labels its Recoil iron shafts F1 to F5, which line up with L, A, R, S and X in its spec tables.
Swing speed, tempo and flex
Swing speed is the usual starting point. Faster swingers with a quicker transition generally benefit from a stiffer shaft, while slower swingers with a smoother transition generally benefit from more flex. Tempo matters because a soft shaft paired with a fast tempo can make the club feel like it lags, while a stiff shaft paired with a smooth tempo can leave you trying to muscle the club through the ball.
The chart below is UST Mamiya's published swing speed recommendation, taken from its Recoil DART graphite iron shaft pages. It uses driver swing speed and driver carry distance.
| Flex | UST Mamiya code | Driver swing speed (mph) | Driver carry (yards) |
|---|---|---|---|
| L (Ladies) | F1 | 60 to 75 | 150 to 190 |
| A (Senior) | F2 | 70 to 85 | 175 to 215 |
| R (Regular) | F3 | 80 to 95 | 200 to 240 |
| S (Stiff) | F4 | 90 to 105 | 225 to 265 |
| X (Extra Stiff) | F5 | 105+ | 265+ |
Note that the ranges overlap, so a golfer at 90 mph could suit R or S depending on tempo and ball flight. This chart applies to UST Mamiya shafts. Charts differ between brands, so always check the chart for the shaft you are considering.
Flex is not standard across brands
There is no industry standard for flex. As True Spec fitter Kris McCormack told GOLF.com, one company's stiff could be another company's X. Flex letters are only relative to other shafts within the same maker's range, so a stiff from one brand may feel quite different from a stiff from another. This is why it pays to compare actual specs rather than the letter alone.
Signs your flex may be too soft
- Ball flight that launches too high.
- Too much spin, often from an early releasing, soft tipped shaft.
- Heel strikes or hooks, as the shaft releases early and shuts the face.
- Less control and inconsistent contact.
- With a fast tempo, the club feels like it lags behind you.
Signs your flex may be too stiff
- Launch that is too low, with reduced carry.
- Too little spin, which can come from tip stiff or heavy shafts.
- Contact pushed toward the toe, as the shaft delays the release.
- With a smooth tempo, you feel you have to muscle the club through the ball.
Launch and spin can also be affected by weight and kick point, so one symptom on its own does not prove the flex is wrong.
Weight and kick point
The flex letter says nothing about a shaft's weight, torque or kick point, and these specs change how a shaft plays.
Weight: heavier shafts can help smooth out a quick transition, while lighter shafts may suit golfers with a smoother, slower tempo. Our driver and fairway wood shafts collection includes a general weight guide.
Kick point: this is the point of the shaft that bends the most during the swing. The lower the kick point, the higher the launch angle, and the higher the kick point, the lower the launch angle. A mid kick point gives a medium trajectory.
Getting it right
A swing speed chart is a useful starting point, but swing speed, tempo, ball flight and feel all play a part. For a precise answer, see a professional club fitter. While you are reviewing specs, check that your lie angle suits you too.
Shop the range:
- All golf shafts
- Driver and fairway wood shafts
- Iron shafts
- Hybrid and utility shafts
- Putter shafts
- UST Mamiya golf shafts
To see the flexes offered with specific OEM heads, browse our shaft spec pages:
- TaylorMade driver and fairway custom shaft specs
- TaylorMade iron custom shaft specs
- PING driver custom shaft specs
- Callaway driver custom shaft specs
- Titleist driver custom shaft specs
Golf Shaft Flex FAQs
What flex should I use with a 90 mph driver swing speed?
On UST Mamiya's published chart, 90 mph sits where Regular (80 to 95 mph) and Stiff (90 to 105 mph) overlap. Your tempo, ball flight and feel help decide between them, and other brands' charts may place you differently.
Is one brand's stiff flex the same as another brand's?
No. There is no industry standard for flex, so one company's stiff could play like another company's extra stiff. Flex letters are only relative to other shafts in the same maker's range.
What happens if my shaft is too stiff?
A shaft that is too stiff can delay the release, push contact toward the toe and give lower launch with reduced carry. Golfers with a smooth tempo may also find themselves trying to muscle the club through the ball.
What happens if my shaft is too soft?
A shaft that is too soft can release early and shut the face, leading to heel strikes or hooks. It can also give higher ball flight, extra spin and less control, and may feel like it lags for golfers with a fast tempo.
Does the flex letter tell me the shaft weight or kick point?
No. The letter says nothing about weight, torque or kick point, so two shafts with the same letter can play very differently. Check the full specs before you buy.
What is kick point?
Kick point is the part of the shaft that bends the most during the swing. A lower kick point gives a higher launch angle and a higher kick point gives a lower launch angle.