Harmony Big Boost - stockWhen it comes to backless boosters – there really isn’t much to rave about. Usually. A backless booster is simply a positioning device meant to boost older kids so that the adult seatbelt fits them properly. A backless booster is usually the last product that older kids will use before they can pass the 5-Step Test and transition to using just the adult seatbelt. Generally speaking, this doesn’t happen until about 10-12 years for most kids although there are always exceptions. The problem with a lot of backless boosters on the market right now is that they don’t actually fit many of the older, heavier kids who still need to use them. Many products claim weight limits of 100 lbs. or more but when you try to stick a kid who weighs 90+ lbs. in the seat, you quickly realize that those numbers don’t translate in the real world. Luckily, bigger kids are not a problem for the Harmony Big Boost Deluxe. It seems to be the ideal booster for kids who may have trouble fitting comfortably in other backless boosters but really still need some help to fit properly in the adult seatbelt. On the downside, it doesn’t seem to fit smaller kids as well and that’s a concern since the minimum weight limit for this product is 30 lbs.

Big Boost Deluxe Specs & Features:

  • Harmony Big Boost DeluxeWeight range: 30 – 110 lbs.
  • Height range: 34 – 57″
  • Age requirements: None (manual indicates that you should consult your state laws for guidance; we suggest this product for kids between 6-12 years old)
  • Child’s ears must be below top of vehicle seat headrest
  • Flexible hook-style lower LATCH attachments with center front adjust strap
  • Well-padded and comfortable
  • Smooth bottom won’t scratch or dent vehicle upholstery
  • Cup holder can be attached to either side
  • Cover is machine washable
  • Shoulder belt positioning strap (if needed) is attached at the bottom


  • Product weight: Less than 4 lbs. (according to my digital bathroom scale)
  • Inside width at hip area: 13″
  • Overall width at widest point: 17.5″
  • Seat depth: 13″ approximately (it’s difficult to measure on this seat)

Belt Fit:

The Big Boost did an excellent job positioning the seatbelt properly on my 11-year-old who is 105 lbs. and 55″ tall.  He raves about how comfortable this seat is and claims it’s the best booster he has ever used! In case you’re wondering why my 6th grader still uses a booster – it’s because the seatbelts in most of our vehicles don’t fit him right yet. He still needs a little boost to be comfortable (and safe!) in the adult seat belt. When he grows a few inches taller (which I’m sure will happen soon), he will pass the 5-Step Test in my van and hubby’s truck. But for now he actually prefers to use a booster. The problem we’ve had is that he doesn’t fit in most boosters on the market today – even the ones that are supposedly rated to 110 lbs. or more. However, as you can see, he fits in this seat and is very happy with it. I specifically asked if he’s bothered by the seat depth because it doesn’t extend all the way down this thighs but he says it’s not an issue. He’s been using this seat for the last 2 months, even on long road trips, and he’s totally comfortable

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On the opposite end of the weight range, here is what belt fit looks like in the same vehicle with a 5-year-old who weighs 37 lbs. and is 43″ tall. The belt fit isn’t terrible but the lap belt placement is a little too low in my opinion (across the femur instead of making contact with the pelvic bones) and when she scooted all the way to one side, she had about 4″ of room between her body and the other side of the booster. My honest opinion is that this product would be best suited for kids who weigh at least 50 lbs.

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Traveling with Harmony Big BoostWhile no booster seat, including this one, can be used on an airplane because airplane seats only have lap belts (and you need a lap/shoulder seatbelt to use any booster), this product does make a great travel seat for older kids. We recently flew with the Harmony Big Boost Deluxe and it fit easily in the overhead bin. It also stored nicely under the seat on the flight home when the overhead bins were full. It’s super lightweight and the front adjuster strap that connects to the lower LATCH connectors made a handy loop for attaching the seat to our wheeled carry-on bag.  If traveling with a backless booster, we always recommend taking it with you as carry-on even though your child can’t sit in it during the flight. A backless booster is small enough to be a carry-on item and if you bring it with you on the plane, it’s nearly impossible for it to be lost or damaged in transit.

Bottom Line:

The Harmony Big Boost Deluxe in a welcome new product for bigger, older kids. It’s super comfortable and it does a great job positioning the seatbelt properly on bigger, older kids. While it isn’t the cheapest backless on the market (MSRP $24.99), it’s a great value for what you get – especially since it’s LATCHable. The only potential downsides are that it’s wide, may not be a great fit on smaller, lighter kids and currently it’s only available at Walmart.

If you’re searching for a comfortable, LATCHable, backless booster and your kid is on the heavier side of the weight range –  the Harmony Big Boost Deluxe definitely deserves your consideration. If you ask my kid, he’ll tell you to go for it because he claims it’s the most comfortable booster he has ever used. That’s an impressive endorsement coming from a kid who has used many different boosters in his short lifetime!