MLB’s base size changes, explained: Why the bases are bigger in 2023 and get ‘pizza box’ comparisons

For those on an MLB diamond this year, there’s going to be a notable difference in the infield besides a restriction on the shift. MLB increased the base size to 18 square inches from the previous size of 15 square inches this offseason, giving the bases more coverage on the dirt.

This change is being made as more of an installation of safety than to affect gameplay. The idea is to avoid collisions, particularly between players covering first base and players running through it.

There may be some small impacts on the field, eg it being slightly easier to steal bases, but they’ll likely be minimal.

The size difference between the bases and the bases of old is somewhat significant.

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How big are the new bases?

The news MLB bases are going to be 18 square inches, up from 15 square inches in past years.

Home plate is remaining the same size.

The difference side-by-side is stark, though fans won’t necessarily see it on television.

Getty Images

Why did MLB increase base sizes?

MLB is increasing base sizes in order to promote player safety and make bang-bang plays less dangerous for defenders and runners.

There is slightly less distance between bases now, so there may be more stolen bases, but that would not necessarily be a “feature” of the new sizes.

Why are bases being compared to pizza boxes?

Red Sox manager Alex Cora had an apt comparison for the new bases.

“The bases, they’re the bases,” Cora said during spring training, per ESPN. “Wait ’til you see them — they look like a pizza box, to be honest with you.”

He also noted the effects — or lack thereof — the change could have.

“Talking to the minor league coaches and everybody that used the rules last year — it’s not that all of a sudden we’re going to steal 100 bags with a guy,” he said.

The difference on the field will probably be small with the new pizza boxes in play. However, if it prevents injury, the change can really only be a good thing.

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