NBA basketball size

What size is an NBA basketball? This question comes up often as NBA enthusiasts and NBA players themselves wonder what size a regulation NBA ball should be. The answer may surprise you, but the NBA has a rather complicated history with basketball sizes! In this blog post, we will go over the specific dimensions of an NBA-sized ball.

As well as the rules associated with these balls in the NBA. We will also mention other leagues such as NCAA, WNBA, and the FIBA that use different basketballs for their games.

What is the Official NBA Basketball Size?

official nba basketball size

NBA regulations state that the diameter of a regulation NBA-sized ball is between 9.43 and 9.51 inches. With a circumference of 29.5 inches (size 7). The weight must be between 20 and 22 ounces. Depending on the surface it will be used on as well as for indoor or outdoor games.

The History of Basketball Sizes in the NBA

The above dimensions were made official in 1979 by the FIBA. Which was then adopted by NBA later that year after the National Basketball Association merged with what had been called the World Basketball League. To form what we know today as simply “the NBA”.

Before this date, there were no guidelines at all for an NBA-sized ball! So how did they end up choosing these specific sizes back in ’79? And why do other leagues have different sizes? Let’s go back in NBA history to find out!

Years of Progressing

In the NBA, basketball size was originally based on a “inches” system. In order from smallest ball to largest, players would start with a 25-inch circumference (similar in size to what is used today for indoor volleyball).

And progress up every inch until they reached their desired 29.5-inch circumference of regulation NBA balls (used since 1979). This included smaller balls like 27-, 28- and 29-inches along the way.

Official in 1979

However, these were not made official by NBA standards until after 1979. When the FIBA came into play with its regulations that were adopted by NBA later that year. The inclusion of these measurements helped standardize game time conditions across any league or court. As it would now be easier for NBA players to adjust to a ball that played differently on an international court or in a smaller NBA arena.

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The NBA has always been extremely open about its basketball sizes and rules regarding them over the years. This is likely because rule changes with size have had such huge impacts on games before. And even what we know of today. At one point, official NBA-sized balls were 15 inches around! In 1979 when the league began using regulation 29.5-inch balls.

They also introduced “smaller” ones for indoor use along with outdoor 27-inch ones. Beginning in 1984 however, all types of official NBA basketballs switched back to the now-familiar 29.5-inch (size 7) regulation size. NBA players today are pretty used to using these sites, but what about other basketball leagues?

history of NBA Basketball size

Other Leagues’ Basketball Sizes

The NBA is not alone in having specific ball standards for its game. Other international and national leagues around the world also have their own rules on NBA-sized balls (and courts). For example, WNBA uses a smaller circumference standard.

Players at any level playing with NBA-sized balls could find themselves at an advantage or disadvantage. Depending on how they adjust to this different rule. The FIBA has two slightly different types of approved “international” sized balls. One that measures 29.5 inches like the NBA and one that is 28.5 inches.

NBA size balls are used in the FIBA-sponsored international tournaments such as the Olympics and World Championships for both women’s and men’s teams. But can be purchased by any player or team to use them outside of these competitions at their own risk.

The NBA does not officially endorse this. NBA ball sizes also vary from those used in NBA Developmental League games. Which measure a slightly smaller 27 inches around.

NCAA Basketball

The National Collegiate Athletic Association (NCAA) also has its own NBA standard basketball size rules for all of its games. NCAA-sized balls are 29.5 inches in circumference and weigh 22 ounces, the same as those used in the NBA-sized.

These smaller diameter sizes were first made official by United States Rubber Company back in 1901. As a “regulation” basketball to be used for high school teams with 11 players on each side; then later adopted by NCAA colleges starting around 1938!

Since NBA regulation is the same, at 29.5 inches, there’s no issue here. College/university students use this specific NBA-standard size while playing within their university or college leagues. Hence, they would not need to adapt if they ever wanted to play outside of them.


NBA-sized balls are also used in AAU (Amateur Athletic Union) games alongside other leagues around the world. This can make it easier for players to adjust back to switch leagues.


The WNBA uses a slightly smaller circumference ball than NBA at 28.5 inches (size 6) but weighs the same as an NBA one at 20 ounces; this makes them more comparable in size with the FIBA’s official “international” standard of 28.5 inches across that has been adopted by many women’s leagues outside of its rule over top division league play like EuroLeague Women or Japan Basketball League (JBL).


FIBA has two slightly different NBA sizes for their official international competition: one measures 29.5 inches and the other 28.5 inches across–this is to accommodate both men and women, as its rules specify that these can be used interchangeably (either way round).

The FIBA allows NBA-sized balls to be used in any of its competitions; but, since those who play with them outside of this must do so “at their own risk,” NBA does not officially endorse such use.

Recommended Basketball Sizes by Age

Basketballs come in different sizes for different age groups. What’s the right size for you?

Recommended NBA-sized basketballs are available in several age groups in the image below;

nba basketball size by age

Basketball recommendations can vary by manufacturer so be sure to pay attention when purchasing your next basketball if you’re not using the specific NBA type of regulation item already.


In conclusion, NBA-sized balls are 29.50 inches in circumference and NBA regulations require that only these particular sized basketballs be used when playing within the NBA league or any other sanctioned event by NBA rules.

Whether playing with friends on the local court or taking part in any sort of official competition that calls for use of either NBA-sized or FIBA ones, NBA size basketballs can be purchased in NBA team colors to suit any player’s tastes.

We hope you enjoyed the article on NBA basketball size and found any resources helpful! We’ll be writing more articles on this website soon, so feel free to come back anytime if you liked what you read about NBA basketballs or need help with something else! Thanks for reading our blog post.

Here are Some of our Favourite Basketball Sneakers

Here we will be giving more of an opinion, rather than facts. Are the sneakers worth the price that they are being sold at? Should you upgrade from your current sneakers, depending on what boots you own? What features stand out on these sneakers? If any. Does it do the job? Speed, control, stability etc. Depending on your needs/preferences. We can also mention its durability, if we have collected enough data on the specific sneakers.

What did we expect vs. what we got. Is it maybe overrated/underrated?


Here’s our pick from the very best of the bunch.


On your way to the pro leagues? Here’s our pick.


Want something to start with? Have a look at our pick.

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