The True3Fit LX is the seat to look at when three car seats have to share one back seat. It measures 16.7 inches across the outside, runs rear-facing from 5 to 40 lb, forward-facing from 22 to 65 lb, and converts to a highback booster from 40 to 100 lb. Graco fits an anti-rebound bar for the rear-facing install and a 10-position harness that moves with the headrest. The number to plan around is the 40 lb rear-facing ceiling, which a heavy two-year-old can reach.
| Seat | Rear-facing | Forward-facing | Booster | Width | ASIN | |
|---|---|---|---|---|---|---|
| 1Graco True3Fit LX | 5-40 lb | 22-65 lb | 40-100 lb highback | 16.7 in | Check price → | |
| 2Britax Poplar S | 50 lb, 49 in | Not listed | None | 17 in | Check price → | |
| 3Evenflo Revolve360 Slim | 4-50 lb, 17-48 in | 30-65 lb, 35-49 in | None | 16.9 in | Check price → |
16.7 inches wide, and the arithmetic that follows
Three seats at 16.7 inches each come to 50.1 inches of seat, and nobody is sitting in them yet. That figure is the one to hold against your back seat, which is not the same as the hip room printed in the brochure. Bolsters, wheel arches and the position of the buckle stalks all eat usable width, and the middle position is usually the tight one because the cushion there is narrower than the outboard seats.
Graco states the three-across claim plainly, with no asterisk. That is unusual. Britax says its 17 inch seat fits three across and then admits in the same breath that it cannot guarantee fitment in every vehicle. Graco skips the hedge, and you cannot tell from the page whether that is confidence or copywriting.
So measure before the return window closes. Our car seat width chart keeps published widths in one place, and the three-across guide covers combinations that people have actually fitted into real cars. Two of these plus a narrow infant seat is the usual plan. Three convertibles is the harder version.
Three modes, three weight windows
The seat covers a rear-facing harness from 5 to 40 lb, a forward-facing harness from 22 to 65 lb, and a highback booster from 40 to 100 lb. Read those windows as overlapping, not sequential. A 35 lb child sits inside both the rear-facing and the forward-facing range, and the seat does not decide for you. Keep them rear-facing while the height limit allows.
Two gaps hide inside those numbers. The listing gives pounds only, with no standing height limits for any mode, so the height ceiling has to come from the manual or the label on the shell. A child who is long in the torso hits a height limit before a weight limit, and the seat stops at whichever arrives first.
The booster is highback only. There is no backless mode, and backless is where most kids land around age eight, when a highback starts blocking the view out of the side window. If you want one seat that runs from the ride home to the end of booster years, this one stops a step short.
The anti-rebound bar and the rule that comes with it
Graco fits an anti-rebound bar to the rear-facing install and describes it as an additional layer of rear-facing safety. The mechanism is simple enough. In a frontal crash the seat pitches forward, then rebounds back toward the vehicle seat, and the bar gives that second movement somewhere to stop.
What the listing does not say is whether the bar comes off for forward-facing. Graco calls it a rear-facing feature and stops there, which leaves the instruction sheet to settle it. Read that page before you spin the seat around. A rear-facing part left bolted to a forward-facing install is exactly the kind of thing that gets missed when a seat is handed down or moved to a second car two years later.
Practical version: keep the manual with the seat, not in a drawer in the kitchen. The person installing this thing in 2029 will not be the person reading this page.
Ten positions, and no rethreading
The Simply Safe Adjust harness has 10 positions, and the headrest and harness move together in one motion. That is the actual convenience. On an older seat you pull the harness out of slots behind the shell, feed it back through higher slots, and hope you got both straps on the same rung. Here the headrest carries the slots with it.
Ten positions across a range that runs from 5 to 100 lb is a coarse grid at the bottom and a finer one at the top. Fine if the fit lands cleanly. Annoying if your child sits between two slots, which is where a lot of four-year-olds sit for a few months.
Set the harness at or below the shoulders for rear-facing, at or above for forward-facing, then check that you cannot pinch slack at the collarbone. The seat will not do that check for you. One failure mode worth naming: the harness looks right because the headrest is right. After a growth spurt, check the slot height first and the padding second. The padding is cosmetic, the slot is structural.
ProtectPlus, and what a crash test claim is worth
Graco’s ProtectPlus Engineered line describes a combination of crash tests covering frontal, side, rear and rollover impacts. It is a claim about a test program, not a published score. No test speeds, no dummy sizes, no comparison data against other brands. Anyone who tells you this seat is safer than another seat is inventing a ranking that the listing does not support.
What you can verify: every seat sold in the US has to meet FMVSS 213, and this one clears that bar by being on the shelf. The extra testing is a reason to trust the shell in impacts outside the standard frontal pulse, particularly the rollover case, which is the one parents ask about and the one most often left untested.
What the listing leaves out matters as much. No seat weight, no recline positions, no install method. If you need a seat that goes in with lower anchors in under a minute, that is a question for the manual, not this page.
Where the True3Fit LX stops
The rear-facing ceiling is 40 lb. That single number decides whether this is your seat. Plenty of two-year-olds are still under it. Plenty of three-year-olds are not, and then the seat has to turn around while the child is still small enough that you would rather they did not.
Compare the field. The Britax Poplar S rear-faces to 50 lb and 49 inches. The Evenflo Revolve360 Slim goes to 50 lb and 48 inches and adds a base that swings the seat toward you for loading. Each of those gives something up in return. The Poplar S has no booster mode. The Revolve360 Slim has no booster either. The True3Fit LX is the only seat in this trio that keeps going through a booster, and the only one that quits rear-facing at 40 lb.
For a compact back seat and an average-sized child, that trade is fine. For a heavy toddler in a roomy car, buy the rear-facing ceiling and give up the booster. Our notes on when to turn a car seat forward-facing explain why the 40 lb line matters more than the calendar. If the seat is headed for a second vehicle, buy that car’s seat separately rather than unbolting this one every morning.
✅ Buy it if
- You need three seats in one row
- Your child is under 40 lb and can stay rear-facing
- You want the same seat to cover booster years
- You want the harness and headrest to adjust together
❌ Skip it if
- Your toddler is already near 40 lb
- You will want a backless booster later
- You need published height limits for each mode
- You want a seat that rotates toward you for loading
Does the True3Fit LX fit three across in any car?
Graco says it fits three car seats across and gives the 16.7 inch width, with no caveat in the listing. That is a claim about the seat, not a promise about your vehicle. Measure usable hip room and check where the buckle stalks sit before you count on it.
What are the rear-facing limits?
The listed range is 5 to 40 lb. No rear-facing height limit is published, so check the manual and the label on the shell. Rear-facing ends at whichever limit your child reaches first.
Can the anti-rebound bar stay on in forward-facing mode?
The listing only calls it a rear-facing feature, which is not the same as an instruction to remove it. Confirm the forward-facing rule in the manual before you change modes, and store the bar with the seat if it does come off.
Is it a booster seat or a harness seat?
Both, in sequence. It is a harnessed seat rear-facing from 5 to 40 lb and forward-facing from 22 to 65 lb, then a highback booster from 40 to 100 lb. There is no backless booster mode.
Last updated: November 2026
Update log: Initial publish — specs taken from the manufacturer listing.