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Golf Shaft Flex Explained: Regular, Stiff or Senior by Swing Speed

Golf shaft flex is how much a shaft bends as you swing, and the right one is decided mainly by how fast you swing your driver. The rough rule: under about 75 mph, a ladies flex; around 75 to 85 mph, senior; 85 to 95 mph, regular; 95 to 105 mph, stiff; above 105 mph, extra stiff. Get it badly wrong and the ball flies too high or too low and misses in a predictable direction. Below is the chart, how to estimate your speed if you have never been measured, the signs your current flex is wrong, and when it is worth paying for a fitting.

What shaft flex actually does

During the downswing the shaft bends back as you load it, then bows forward and kicks the head through impact. A shaft that suits your speed returns the face square with a launch and spin that carry the ball well. Too soft and the head arrives with the face closed and the loft added, so shots fly higher and tend to go left for a right-hander. Too stiff and the face arrives open with less loft, so shots fly lower, tend to go right, and the strike feels harsh and dead.

There is no industry standard. One maker's regular can be stiffer than another's, and a "stiff" iron shaft and a "stiff" driver shaft are measured differently. That is why the speed bands below are a starting point rather than a rule.

Shaft flex chart by swing speed

Carry means how far the ball flies in the air before it lands, not the total with roll. Most golfers overestimate both: if you are not sure, take your honest average carry on a calm day, not your best drive of the summer.

How to estimate your swing speed

• Get measured. A launch monitor at a fitting studio, a shop or a range bay with ball tracking gives your club speed in a few swings. This is the only reliable number.
• Use your carry. Carry distance with a driver is roughly two and a half times your swing speed in mph for a good strike (a little more for faster swingers), so a 220-yard carry suggests around 88 mph and a regular flex.
• Use your 6-iron. If you hit irons more consistently than a driver, the 6-iron column above is often the more honest guide.

Signs your flex is wrong

A slice is not always a flex problem. Most slices come from an open face or an out-to-in path, and a softer shaft will not fix them. If you slice every club in the bag, see our guide on how to hit a driver straight before you spend money.

Tempo matters as much as speed

Two golfers with the same 90 mph driver speed can need different shafts. A smooth, slow transition from backswing to downswing loads the shaft gently and often suits a softer or lighter shaft. A quick, aggressive transition loads it hard and usually needs a stiffer one. This is the main reason fitters watch you hit rather than read a chart.

Shaft weight, steel and graphite

Flex is only half of the shaft. Weight changes how fast you can swing and how the club feels. Steel iron shafts typically weigh around 95 to 130 grams; graphite iron shafts are lighter, often 50 to 90 grams, and absorb more vibration, which is why they suit seniors, many women and anyone with sore joints. Drivers and woods are almost all graphite. If you are moving to senior flex because your speed has dropped, a lighter shaft often helps as much as the flex change. Our guides to golf irons, drivers and ladies' golf clubs cover the clubs the shafts go in.

Is a fitting worth it?

If you are buying a new driver or a set of irons, yes. A fitting tests several shafts on a launch monitor and often costs little or nothing if you buy through the fitter. For a beginner with a starter set it matters less: most box sets come in regular flex for men and ladies flex for women, which suits most new golfers. Our golf club fitting guide explains what happens at a session.

Test it at Lullingstone Park

The quickest way to feel the difference between flexes is to hit a bucket of balls and then take the club onto the course. The practice facilities at Lullingstone Park are open to visitors, and the Castle Course rewards a straight driver more than a long one. Check the green fees and book from the Lullingstone Park homepage.