Should I get a 9.5 or 10.5 degree driver?

Start from the launch windows in this report. An average amateur at 84-96 mph wants 13-16 degrees of launch and 2,400-2,700 rpm, slower swings want 14-19 degrees, and only the 105 mph-plus group is comfortable down at 10 degrees of launch. A loft guide that compiles TrackMan optimiser data turns that into a static loft: 10.5-12 degrees at 85 mph, 10.5 at 95, 9-10.5 at 105 and 8-9.5 at 115. On those figures, 9 or 9.5 degrees is a fast-swing loft.

Attack angle moves the answer more than speed does. A downward strike takes loft off at impact: the same guide estimates that a 10.5-degree driver hit 3 degrees down delivers roughly 7.5 degrees, and suggests about one extra degree of static loft per degree of downward attack. A 9-degree head needs both speed above about 100 mph and a level-to-upward strike, which most amateurs do not have. The independent test's own advice for slower swings is the same: if launch, spin or peak height is too low, add loft and a shaft that raises them.

Adjustable hosels blur the choice without removing it. Adding loft at the sleeve also closes the face and changes the lie, so a 9.5-degree head set to 10.5 does not sit or start the ball like a 10.5 at neutral. On a used driver, ask for both the printed loft and the sleeve setting.

These are starting points. The fitting study behind this report found its gains came mostly from raising launch and lowering spin, which is loft and shaft work done on a launch monitor. If you are buying without a fitting and are not sure, 10.5 degrees is the safer default for most golfers.