Harmony Big Boost Deluxe Review

(Last Updated On: )

Harmony has issued a recall for their Big Boost Deluxe booster seat due to the possibility of excessive force on the child’s chest in the event of a crash. At this time, there isn’t a remedy for this recall.


The remedy for this recall is still under development. The manufacturer has not yet provided a notification schedule. Owners may contact Harmony customer service at 1-877-306-1001.

Owners may also contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236 (TTY 1-800-424-9153), or go to www.safercar.gov.

Harmony Big Boost Deluxe

Harmony Big Boost Deluxe

Harmony makes just a few car seats — the Defender 360 combination seat, the Youth Booster, and the Big Boost Deluxe.  We’re fans of the Defender and the Youth Booster so we were eager to spend some quality time with the lowest priced backless booster that includes LATCH on the market!

For a seat with a ridiculously low $24.99 retail price, the lower anchor connectors are a nice feature. The Big Boost Deluxe also includes a cupholder and an attached shoulder belt guide.  It also features a name that reminds me of a hamburger.

CSFTL Quick Stats

  • Weight range: 30-110 pounds
  • Height range: 34-57 inches tall
  • Expiration: 10 years


  • Width at widest point: 17.5 inches
  • Width at narrowest point: Rounded shape makes this impossible to state
  • Seat pan depth: 12.5 inches
  • Weight: 3.5 pounds

Carpooling Essentials

  • Easy to set up without (very much or any) adult assistance
  • Easy to carry
  • Consistent belt fit


The Big Boost Deluxe requires just a little setup to use with lower anchors.  It ships with the lower anchor connectors, cupholders, and shoulder belt guide tucked into the bottom of the seat in a very tidy way. Removing the lower anchor connectors from this setup took a little effort — I had to loosen the webbing, then push the connectors through the little slot in the seat’s bottom to free them. Once they were loose, the lower anchor connectors clipped right into my vehicle’s lower anchors and the seat was ready to go.

Three Across

Harmony Big Boost Deluxe three across

Harmony Big Boost Deluxe three across

I had the chance to try the Big Boost Deluxe as part of a challenging three car seats across situation — a Cosco Scenera NEXT, a Graco SnugRide 30, and the Big Boost Deluxe in a 2015 Hyundai Tucson.

Our model was able to buckle herself in without issue, which made this vehicle workable for the growing family!  She had a better fit with the attached shoulder belt adjuster but unfortunately, was all done modelling for pictures by that point.

Note: the Chicco GoFit also worked in this configuration.

Tapered Back

Harmony Big Boost Deluxe tapered back

Harmony Big Boost Deluxe tapered back

The Big Boost Deluxe’s seat back tapers in toward the middle.  This makes reaching the vehicle seat belt buckle pretty easy for some  booster riders — even when the Big Boost Deluxe is part of a fairly tight three car seats across situation!

However.  This unique shape means that in some vehicles with a contoured seat. the seat belt bunches up around the buckle and our youngest model had a pretty hard time accessing the buckle.

Unique Restrictions

The manual contains this warning: Do not use with lap belts whose anchor points are forward of the seat bight.  So if the vehicle seat belt is attached to the vehicle in front of the seat bight — the place where the vehicle’s vertical seat back meets the vehicle’s horizontal bench portion — then the Big Boost Deluxe won’t work in that vehicle.

The manual also includes a recommendation that the seat belt be locked when the booster is in use. Harmony is the only manufacturer to make this particular suggestion.

Fit to Child

7.5 Years Old

Harmony Big Boost Deluxe 7 years old

Harmony Big Boost Deluxe 7 years old

This seasoned booster rider is 7.5 years old, wears a size 8 clothing, and is 50 inches tall. She didn’t find the Big Boost Deluxe to be all that comfortable, but she loved the cup holder! The shoulder belt fit without the adjuster was kind of hit or miss but since it’s attached to the Big Boost Deluxe, accessing the adjuster was pretty simple.  The lap belt fit was a little low on her thighs but within the acceptable range.

Our biggest issue with the Big Boost Deluxe for this model in this seating position was adjusting the lap belt.  It took a lot of effort for her to tighten the lap belt and even then, it bunched up under the armrest no matter how hard she pulled on the lap portion of the vehicle seat belt.  We have some pretty serious concerns around kiddos being able to use this booster correctly.

Five Minutes Later

Slouching in the Harmony Big Boost Deluxe

Slouching in the Harmony Big Boost Deluxe

The Big Boost Deluxe’s shape inspired our model to slouch down into the seat.  Oddly, in this position, the lap portion of the vehicle seat belt didn’t gather quite as much under the armrest.

This kind of inconsistent belt fit gives us a lot of hesitation around using this seat.

11 Years Old

Harmony Big Boost Deluxe

Harmony Big Boost Deluxe

This 11-year-old model is at the top end of the Big Boost’s height range but well under the 110 pound maximum. She’s an experienced booster rider with a lot of thoughts about what she rides in. She found the Big Boost Deluxe’s rounded back a little odd. The rounded back made her feel more squashed than she might have with a more open style of seat pan. Thanks to the flared sides, reaching the seat belt buckle was no problem for her, even in vehicles with buckles that are tough to access.

Important Information: Where to Find

Harmony Big Boost Deluxe date of manufacture and FAA restriction labels

Harmony Big Boost Deluxe date of manufacture and FAA restriction labels

FAA Approval: like all booster seats, the Big Boost Deluxe is not approved for use on aircraft. That’s because airplane seat belts are lap only belts and booster seats require a lap and shoulder belt. However, the Big Boost Deluxe could store easily in the overhead bin of an airplane and be ready for use upon arrival.

Harmony Big Boost Deluxe date of manufacture label

Harmony Big Boost Deluxe date of manufacture label

Date of Expiration: the date of manufacture label is on the bottom of the seat. The Big Boost Deluxe expires 10 years after the date of manufacture.

Manual Storage: the manual stores underneath the cover, toward the front of the seat.

Overall Thoughts

The Big Boost Deluxe has a lot to offer — it’s lightweight, is reasonably priced, has lower anchors, and is easy for carpoolers to carry around and set up by themselves. However… we’ve got a few concerns. The seat pan’s unusual shape may be a hard sell for some kiddos. The way the seat belt bunches up at the armrest is concerning. Add in the way our models tended to slouch while sitting in the Big Boost Deluxe and we’re hard-pressed to make it our go-to booster for carpools.  Families who need three seats across may find that it works for their situation but the belt fit is so inconsistent, it wouldn’t be our first choice.