Softer than you think. The IRF rules put a roundnet ball between 2000 and 3500 pascals, which is 0.3 to 0.5 PSI. Inflate it until it holds a round shape and still gives clearly when you press hard with a thumb. If it feels like a tennis ball, let air out.
Hold the ball in one hand and press hard with your thumb. It should dent visibly and spring
straight back. Not squash flat. Not resist you like a rock. Somewhere in between, and much
closer to the soft end than anyone expects on their first try.
Then drop it on the net. A correctly inflated ball on a correctly tensioned net comes back
fast and predictably. If it thuds and dies, one of the two is wrong, and the honest way to
find out which is to test them separately. The net has its own drop test, which is on
the setup page.
"Why not just give me a PSI number, Jakub?" I did, it is in the first paragraph. The problem
is that 0.3 PSI sits below the useful range of the gauge on a normal pump. You would be
reading zero and guessing anyway.
What the rulebook actually specifies
Three numbers. All from the International Roundnet Federation ruleset:
Weight: 85 g, with a tolerance of 5 g either way.
Circumference: 330 mm, with a tolerance of 10 mm.
Pressure: between 2000 and 3500 pascals, which is 0.3 to 0.5 PSI.
There is a fourth line that people skip over, and it is the one that matters most for you at
home: the ball has to allow internal pressure adjustment. A roundnet ball is built to be
tuned. That is not an accident and it is not a manufacturing shortcut, it is a design
decision, and it is what lets you make the same ball right for a six year old and right for
a tournament.
About the size, since the numbers do not help much: 330 mm around puts it somewhere between a
grapefruit and a small melon, and 85 g makes it far lighter than it looks. That combination
is why it moves the way it does.
There was no pump in the box
Any ball pump with a needle does the job. The same needle that goes into a football or a
basketball, and a bike pump with a needle adapter works fine too. Sports shops sell the
needles for the price of a coffee. Most households with a child already own one.
One warning, because it goes wrong in the other direction to what you would expect. At this
pressure you are not fighting to get air in, you are trying not to put too much in. A couple
of strokes, check by hand, a couple more. Overinflating is the standard first mistake and it
makes the ball painful to receive.
Wet the needle before it goes in. Dry needles tear the valve, and a torn valve is a dead ball.
Why half a PSI changes the whole game
A hard ball is a fast ball. It leaves the net quicker, gives you less time, punishes every
small error in your first touch, and stings the forearms of anyone who is still learning to
receive. A soft ball does the reverse: slower off the net, more time, more rallies, and it
forgives a bad contact.
Neither is correct in the abstract. They are correct for different people. Put two
identical teams on a hard ball and a soft ball and you get two different sports, which is
exactly why the tournament rules pin the range down instead of leaving it to whoever brought
the set.
This is the single cheapest adjustment in the whole game. It costs nothing, takes ten
seconds, and it changes more about how an evening in the garden feels than any technique tip
I could give you.
Is the ball too hard for children?
It might be. The fix is not a different ball. Let air out of the one you have.
Take it to the soft end of the range, or a little under it if nobody is keeping score. The
ball slows down, the hands stop hurting, and rallies suddenly last four or five touches
instead of one. Children do not quit because a game is hard, they quit because nothing ever
comes back over. Longer rallies fix that in an afternoon.
Same trick for adults who have never played a ball sport, by the way. Nobody has to know.
Why your ball feels different today
Two reasons. Both boring. Balls lose air slowly, all of them, and cold air takes up
less room. A ball that was perfect in August will feel flat on a cold morning and needs a
couple of strokes before you start.
Balls are consumables. They go soft, the surface wears smooth, and one day they stop
holding their shape. Competitive players get through them and think nothing of it. Keep one
spare inflated in the bag and you will never lose an evening to it.
Common questions
Press your thumb into the ball right now. If it barely moves, you have found the reason the
game felt harder than it should.
Quick guide: the world championship in brief
How much should I inflate a Spikeball ball?+
The IRF rules put the internal pressure between 2000 and 3500 pascals, which is 0.3 to 0.5 PSI. That is very low, low enough that most pumps and gauges cannot measure it at all. In practice you inflate until the ball holds its round shape and still gives clearly when you press it hard with a thumb. If it feels like a tennis ball it is far too hard.
There was no pump in the box. What do I do?+
Any ball pump with a standard needle works, the same needle used for footballs and basketballs. Bike pumps with a needle adapter work too. Because the target pressure is so low, the risk is overinflating in one squeeze rather than not getting enough air in, so go slowly and check by hand between strokes.
How big and how heavy is a roundnet ball?+
The rules specify a weight of 85 grams with a tolerance of 5 grams, and a circumference of 330 mm with a tolerance of 10 mm. So it is roughly the size of a large grapefruit and much lighter than it looks.
Why does my ball feel dead?+
Either it has lost pressure, which every ball does slowly, or it is cold. Air pressure drops with temperature, so a ball that played well in August feels flat on a November morning. Add a little air and check it again by hand.
Is there a softer ball for children?+
You do not need a different ball, you need less air in the one you have. A roundnet ball is designed for pressure adjustment, and taking it toward the soft end of the range makes it slower, more forgiving on the hands and much easier for a child to control. It also makes rallies last longer, which is the whole point at that stage.
Does ball pressure really change the game?+
More than beginners expect. A harder ball comes off the net faster and punishes small errors, a softer ball travels slower and rewards control. Two teams of the same standard will have completely different games on a hard ball and a soft one, which is why tournaments regulate it.
When should I replace the ball?+
When it stops holding air between sessions, when the surface is worn smooth enough to change how it grips, or when it no longer holds its shape. Balls are consumables and competitive players go through them, so keep a spare inflated and ready.
