How many dimples are on a golf ball?
Most balls on sale today have about 300 to 450 dimples.
There were a few balls having over 500 dimples before. The
record holder was a ball with 1,070 dimples -- 414 larger ones (in
four different sizes) and 656 pinhead-sized ones. All brands of
balls, except one, have even-numbered dimples. The only
odd-numbered ball on market is a ball with 333 dimples.
Officially sanctioned balls are designed to be as symmetrical as
possible. A ball can have six rows of normal dimples on its
equator, and very shallow dimples elsewhere. This asymmetrical
design helps the ball self-adjust its spin-axis during the flight.
The USGA did not sanction it and changed the rules to ban
aerodynamic asymmetrical balls. The ball supplier sued the USGA and
the USGA paid U.S. $1.375 million in an out of court
The number of dimples on a golf ball varies, depending on the
manufacturer and may even be different for different models made by
the same manufacturer. The dimples are usually the same size as one
another, but some golf balls have several different sizes of dimple
on the same ball. Any number between 300 and 500 dimples is
reasonable, and 336 is a common number. Not just any number will
do. Golf balls are usually covered with dimples in a spherically
symmetrical way, and for many values of N, it is impossible to
cover the golf ball uniformly without gaps. Symmetry is important
or the ball will wobble or its flight will depend on which part of
the ball is forwards or sideways as the ball spins. You can get an
idea of how to space dimples uniformly around a sphere by thinking
about the "platonic solids" -- the tetrahedron, cube, octahedron,
dodecahedron and icosahedron, and placing a dimple at the corners
of an inscribed platonic solid. Variations on this theme give the
corners of Buckminster Fuller's geodesic domes, and also the
possible symmetrical locations of dimples on a golf ball.
Why does a golf ball have dimples on its
When a golf ball is flying through the air, it has three forces
on it. Two of them are gravity and drag from the air. In addition,
if the golf ball is spinning, there will be a Magnus force on it
(which may point up or down or either side, depending on how it is
spinning -- the Magnus force cannot point along the flight path of
the ball however -- see our answer on the Magnus force for more
The main goal of making a golf ball go farther however is to
reduce the force of drag as it flies through the air. In general,
turbulence increases drag, because the energy needed to stir the
air up and make it swirl around is energy that the ball has lost.
One might think that a rough ball will induce more turbulence in
the air than a smooth one, but it depends on how fast the ball is
going. For balls going slowly through a viscous fluid, then the
fluid just moves a bit to the side as the ball passes, and then it
returns more or less to where it was. If the fluid motion is
smooth, we call the motion "laminar", otherwise it is "turbulent."
A ball moving quickly through a fluid like the air will have air
flowing in a laminar fashion in some places and in a turbulent
fashion in others. Directly behind the ball there will be a
turbulent "wake", and surrounding that will be smoothly flowing
air. The whole idea behind reducing the drag is to make the
turbulent wake small.
The air that slides past the ball very close to it is called the
"boundary layer". At the place where the turbulent wake starts is
called "separation of the boundary layer" where the smoothly
flowing air departs from the ball and does not close up behind the
ball nicely but rather swirls around in small vortices. If the
boundary layer can be encouraged to stick to the ball a little
longer, then the turbulent part of the wake can be reduced. It
turns out that adding a little extra turbulence in the boundary
layer itself all over the ball allows the main smoothly-flowing air
currents to stay closer to the ball and delays the separation of
the boundary layer. Some nice pictures of balls in wind tunnel
showing this effect can be found here.
There is also an increase in the Magnus force, giving the ball
some lift when it is spinning in the correct direction. This force
helps keep the ball in the air longer, allowing it to travel
People have thought of putting dimples on everything from
swimsuits to cars to airplanes. You only get an advantage from
these dimples if the boundary layer can be made to stick longer to
the object. Some cars just have vertical flat ends to them where
the trunk comes down and there is no way to reduce the turbulent
wake of these no matter how dimpled the paint is. And the boundary
layer stays with airplane wings except maybe a bit at the ends
(some gain can be made by putting small rods out on the tips or on
the trailing edges of the wings).