Three Across Update

3 car seats or booster seats across isn't always fun

3 car seats or booster seats across isn’t always fun

Installing three car seats or booster seats in one row or having three passengers in one row is one of the biggest challenges a growing family can face when it comes to car seats. We call this scenario Three Across and it can apply to a few situations:

  • Three car seats in one vehicle row
  • Three booster seats in one vehicle row
  • Two car seats and one passenger who does not need a car seat or booster seat in one vehicle row
  • One or two harnessed car seats or booster seats plus one passenger who does not need a car seat or booster seat in one vehicle row
  • Any combination of three harnessed seats, booster seats, and passengers in one vehicle row

The words “three across” might send fear down the spine of any caregiver or CPST, but they don’t have to!

We tend to consider this scenario the Holy Grail of car seat installation because it presents a number of unique challenges. We’ll break down the different elements that come into consideration when installing three car seats in a row, and hopefully we will take the fear out of getting your setup set up.

A room full of car seats!

A room full of car seats!

There isn’t one answer for every three across situation.

While we can make some suggestions based on our experience, in the end, getting to a setup that works well usually requires some trial and error. And often some cursing or angry words.

Tether connected to tether anchor

Top Tethers Install forward facing harnessed seats in seating positions where there are top tether anchors. The top tether provides a significant safety benefit for a forward facing child. For a sedan, this usually isn’t an issue because almost every sedan has 3 tether anchors for the back seat. However, in an SUV or minivan, all bets are off. The third row may have 3, 2, 1, or 0 tether anchors so three forward facing harnessed car seats not work in that particular row.

Booster seat buckle access is important! Side view of seat belt buckled over purple booster seat.

Booster seat buckle access is important!

Booster Seat Buckle Access Loading children into car seats when there are three across is often easier with three harnessed seats than with booster seats.

While the small hands of children might fit in these spaces, children often lack the dexterity to buckle the seat belts in between seats. Adult hands often simply don’t fit. And if the car seat next to the booster is installed with the seat belt, when the booster rider reaches to unbuckle her seat she may accidentally uninstall her brother’s seat; trust us when we say from experience: this is a headache well worth avoiding.


Lower anchors

Lower anchors

Vehicle Seat Belts vs. Lower Anchors

In many cases, installing car seats with the vehicle seat belt can help create additional horizontal space on the vehicle seat. Lower anchors attach to the vehicle in only one spot — the lower anchor connector on the car seat has to connect directly to the vehicle lower anchor in front of it, there isn’t much flexibility side to side in terms of where the car seat fits on the car’s seat. Seat belt installations don’t have that requirement — the car seat can scoot toward either side of the seating position and still have a secure installation. An exception might be vehicle seats with high side bolsters, as the car seat may not install securely with half on a bolster.

Lower Anchors in the Center Vehicle Seat

Some vehicles have a dedicated set of lower anchors in the center vehicle seat. In some cases, installing a narrow car seat in this position using the lower anchors can free up space in the outboard seating positions, allowing for seat belt installations in the outboard seats.

Lower Anchor (LATCH) Borrowing

The use of the inner lower anchors of the outer seating positions to install with LATCH in the center is known as “LATCH borrowing”. Many vehicle manufacturers and seat manufacturers prohibit this. Before using the lower anchors in the center position, be sure to check with both your particular seat manufacturer and vehicle manufacturer. If you can’t LATCH borrow, you can usually still install in the middle using the seat belt.

Vehicle Seat Belt Overlap

Overlapping vehicle seat belts: buckle portion of center seat belt crosses lap portion of side seat belt

Overlapping vehicle seat belts

In some vehicles, the seat belt for the middle seat either anchors or buckles within the seat belt span for a side seat. This results in a situation where the belts or lower anchor straps might interfere with another car seat. In some cars, because the overlap is so severe, a three across setup isn’t possible at all.

Car Seat Height

It’s not just the width of the car seat that factors into which seats will work together — sometimes the car seat’s height matters as well. In some instances, car seats can sit next to each other in configurations we wouldn’t have expected. By the opposite token, sometimes a tall forward facing seat in a third row will rapidly approach the roof, which will then be an issue as the child grows.

Car Seat Shape

Tan Chicco GoFit on display table

Chicco GoFit

In most cases, the more square a car seat is, the more likely it is to fit next to another car seat or between two car seats. Seats that have a lot of contours don’t tend to fit next to other car seats, unless the contours coordinate in exactly the right way!

Important Note: some manufacturers don’t allow the edge of one car seat to sit over the edge of another car seat. In other words, they want you to imagine a glass wall between the seats that can’t be crossed. Always check with the car seat manufacturer of each seat involved if you come upon this scenario.

Alternate Directions

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Sometimes it is convenient to load the rear facing child in through the back hatch

Installing three car seats across is sometimes easier if the seats alternate directions. This could translate to: a booster seat outboard, a rear facing car seat in the center seating position and a forward facing car seat or booster in the other outboard position.

Another set-up that makes use of alternating directions: a forward facing car seat outboard, a rear facing car seat in the center seat, and a forward facing car seat outboard.

This variation in direction can sometimes offer more room to older booster riders.

Ease of Use/Loading Access

While a rear facing car seat may install best in the center vehicle seat, if it’s impossible to get the child buckled in to the seat, it doesn’t matter if the seats fit. Sometimes, loading a child through the rear hatch of a van or hatchback can make a rear facing seat in the back row work.

Third Row Booster Seat Challenges

Evenflo Spectrum

In the popular Town and Country minivan and other vehicles with three or more rows, the third row presents a few unique challenges for booster riders. The angle of the seat belt mount in the outboard seating positions puts the vehicle seat belt in an awkward location across the passenger — several inches forward of the shoulder.

A backless booster isn’t a great choice for the third row because a backless booster on the larger portion of a split bench seat will not have adequate head support in a three across.

We’ve looked high and low to find solutions for this issue but they’re few and far between. We’ve even written an article about the frustrations of the third row in a Mazda 5.

We’re still looking for the totally consistent booster seat option for that seating position. We’ve had mixed results with the Evenflo Spectrum and the Kiddy Cruiser 3.

Overhang, Footprint, and Other Considerations

Rear facing convertible seat installed on captain's chair of van with part of the base hanging off the side of the car's seat

Side overhang

Other factors to consider are how car the car seat hangs over the sides of the vehicle seat, which is not allowed by some manufacturers; how much front to back space an installation requires; and making sure each seat is independently tight.

All car seats must be properly installed, and independently tight. This means that if one car seat is uninstalled, the other car seats are still installed correctly, with less than an inch of movement at the belt path. Adjacent car seats can’t keep the other car seats installed correctly — each car seat in each configuration must be installed correctly.

In Summary

As you can see, there are many factors involved in achieving a safe and correct three across installation. We hope this article has helped you, and please feel free to post in our Facebook group or message this page with specific questions!