What it measures
Ball speed is the speed of the ball's center right after it leaves the face, measured in miles per hour. Like club speed it has no direction, so it is always positive and does not depend on whether you swing right or left handed.
It is an outcome of impact, combining how fast the club was moving with how well the ball was struck.
Typical numbers
PGA Tour players average about 171 mph of ball speed with driver and LPGA Tour players roughly 140 to 143 mph. Tour 7 iron ball speed usually sits around 120 to 123 mph for men and in the low 100s for women, with pitching wedges lower still.
The average male amateur produces around 133 mph of ball speed with driver, a 10 handicap near 138 mph and a scratch player around 161 mph. Female amateurs range from about 111 mph at a 15 handicap to around 131 mph at scratch. Iron ball speeds for everyday golfers often sit between about 90 and 115 mph with a 7 iron.
What changes it
Club speed is the starting point: more speed raises the ceiling. Strike location is next. Hits off the toe, heel, top or bottom of the face lose speed, sometimes several mph on a driver. A glancing blow, where face and path point in quite different directions, also costs speed, as does too much spin loft, such as hitting too far down with a driver or adding loft at impact.
Equipment matters as well. Lower lofted clubs, faster faces and well fitted shafts all help convert club speed into ball speed.
What it changes
Ball speed drives carry and total distance more than any other number. One extra mph of ball speed can add up to about 2 yards with driver. It also affects spin: harder hit shots tend to spin more for the same delivery. Combined with launch angle and spin rate, ball speed decides height, landing angle and how far the ball rolls.
How to use it
Read ball speed next to club speed and smash factor. If ball speed is low but club speed is good, the problem is contact, not effort. If both are low, speed training will help more than strike work.
In the bay, try a centered strike challenge: hit ten drives at normal effort and record the highest and lowest ball speed. Then focus only on center contact and try to shrink that gap. A tighter ball speed spread usually means tighter distance control on the course.