Baseball News
Bigger Bases, Bigger Impact: What MLB's 18-Inch Bases Mean for Clubs
This blog tells you everything you need to know, the differeces between the bases and what we might expect soon.
Last updated: 2 December 2025 | 3 min read
If you’ve been following Major League Baseball, you’ll know that MLB switched from the traditional 15-inch square bases to larger 18-inch versions starting in 2023. This season, college baseball has followed suit, meaning the change is spreading beyond the pros. It’s only a matter of time before other national leagues, such as the KNBSB (Royal Dutch Baseball and Softball Federation), implement the same standard.
So what’s the difference, and what should clubs know before the switch becomes official?
The Difference: 15-Inch vs. 18-Inch Bases
Old size (standard for decades): 15 x 15 inches (38 x 38 cm)
New size (MLB & NCAA): 18 x 18 inches (46 x 46 cm)
At first glance, three inches may not sound like much. But because the bases are square, each side is three inches longer, meaning the bases take up more field space. Most importantly, the distance between first and second base (and between second and third) is shortened by 4.5 inches overall. That’s because both bases extend further toward the other. If you are looking for 18-inch bases, you have come to the right place! Forelle is one of the few dealers that offer this base size.
Why the Change Was Made
- Player Safety
The larger bases provide more surface area, reducing collisions on bang-bang plays.
Infielders and runners now have slightly more room to avoid stepping on each other’s feet.
- More Action
With a shorter distance between bases, stolen base success rates rise.
MLB saw a jump in stolen base attempts and success percentages after the switch.
- Game Tempo
By encouraging more steals and aggressive baserunning, the larger bases contribute to faster, more dynamic play.
What This Means for Clubs in European Leagues
When (not if!) the KNBSB and other federations adopt 18-inch bases, clubs will need to prepare for both financial and on-field changes.
- Facilities & Equipment
Base sets: Current 15-inch bases will need to be replaced with regulation 18-inch versions.
Anchors & Pegs: Check whether existing base anchors can accommodate the larger bases. In many cases, new anchors may need to be installed to ensure proper fit and safety.
Infield dimensions: The distance from home to first and third remains 90 feet, so no field re-marking is required. However, base cutouts in turf or dirt may need to be widened.
- Coaching & Strategy
Running game: Expect more opportunities for stolen bases and hit-and-run plays. Coaches should emphasize baserunning in practice.
Defensive drills: Infielders will need to adjust footwork around the larger bag, especially on double plays and pickoff attempts.
Pitchers & catchers: With shorter steal distances, holding runners on base and making quick throws will become even more important.
- Player Adaptation
Runners: Need to learn how to take slightly more aggressive leads and sharper turns.
Fielders: Must practice positioning and tagging on the wider surface.
Youth players: For clubs with multiple age groups, consider phasing in the new bases early so players adjust smoothly.
The Bottom Line
The move to 18-inch bases is here to stay. MLB data shows it makes the game safer and more exciting, and federations worldwide are likely to follow. For clubs in Europe, the change won’t drastically alter field layouts but will impact equipment, player habits, and tactical strategies.
Now is the time for clubs to plan ahead—whether that means budgeting for new bases, reworking infield cutouts, or introducing players to the nuances of the larger bags. Bigger bases may seem like a small change, but they’re set to play a big role in the future of baseball.