1 / 1 Image from Nuna

Image: Nuna, from nunababy.com. Colors may differ from the seat you buy. See it on nunababy.com

Nuna AACE booster seat

A 2-in-1 booster seat with 2 modes: high-back booster 40 to 110 lb, 43 to 60 in; backless booster 50 to 120 lb, 43 to 60 in.

At a glance

Fits children from 40 to 120 lb
Up to 60 in tall
2 modes: high-back booster, backless booster
Seat weighs 15.6 lb
10-year usable life

$300.00on nunababy.com, as of 2026-10-07 05:48 UTC. Prices change.

Buy from Nuna

Sold by Nuna. Not an affiliate link; this site earns nothing from it.

Nuna product page Manual

Specifications checked against Nuna’s US site and manual on September 17, 2026. Not hands-on tested. How I research

Who is the AACE booster seat for?

The Nuna AACE is a booster that converts from high-back to backless. High-back mode: at least 4 years old, 40 to 110 lb and 43 to 60 in. Backless mode: at least 5 years old, 50 to 120 lb and 43 to 60 in. It uses the vehicle lap and shoulder belt and expires after 10 years.

Reasons to consider it

Converts to a backless booster for children 50 to 120 lb
9-position headrest, with sides that widen as it rises
Rigid lower anchor connectors keep the booster secured when empty
3 seat depth positions for thigh support

Things to weigh up

Not certified for aircraft use
Cannot be installed with lap-only, motorized or door-mounted belts
Nuna's page lists an 8-position recline with the lower anchors, but the manual warns never to use the booster reclined beyond recline position 2
No recline in backless mode

My take on the AACE booster seat

The AACE suits a child who has outgrown a harness and can sit still in a lap and shoulder belt for the whole ride. It goes to 60 in in both modes, while the booster modes on Nuna's LUMN and EXEC next stop at 57 in. The main thing to check is the vehicle: it needs a 3-point belt, and the rigid lower anchors only hold the booster in place.

A research summary of Nuna’s published specifications and manual, read October 7, 2026. Not a hands-on test or a crash-safety rating.

Who the AACE booster seat fits

This seat covers 2 stages, and a child has to meet every limit of the stage they are in. Nuna gives it a 10-year life from the date of manufacture, so check the date label before using a hand-me-down.

High-back booster40 to 110 lb · 43 to 60 in · from 4 years: The seat’s own back and belt guide route the vehicle belt across the shoulder, and the sides give the child something to lean on when they sleep.
Backless booster50 to 120 lb · 43 to 60 in · from 5 years: Only the base is left, so the vehicle seat has to support the child’s back and head, and the belt guide sits at the hip.

A school-age child with a backpack beside an empty high-back booster

What are the AACE booster seat weight, height and age limits?

Nuna AACE booster seat limits by mode
Mode	Child weight	Child height	Minimum age	Conditions
High-back booster	40 to 110 lb	43 to 60 in	4 years	At least 4 years old
Backless booster	50 to 120 lb	43 to 60 in	5 years	At least 5 years old

A child must meet every limit for the mode they use. The labels on your seat and its manual are the final word.

AACE booster seat specifications

Seat weight: 15.6 lb
Width: Not published
Usable life: 10 years
Aircraft use: Not certified for aircraft
Dimensions, highest setting: L 15 × W 22.5 × H 33 in
Dimensions, lowest setting: L 14.6 × W 21.5 × H 26 in
Headrest positions: 9
Recline positions high back: 8
Seat depth positions: 3

How the AACE booster seat installs

Lower anchors: Lower anchor connectors. Check your vehicle manual for which seating positions have anchors, and switch to the seat belt once the child passes the anchor weight limit in the manual.
Recline: 8 recline positions in high-back mode (with lower anchors). The recline angle is what keeps a young baby’s airway open, so set it before tightening the install.

Every install is a fit between one seat and one vehicle. Read both manuals, and use a free inspection station if anything is unclear.

An empty car seat installed on a back seat, seen through an open car door

Will it fit your car?

Nuna does not publish a width for this seat, so measure your back seat and compare it with the seat in a store before buying. It weighs 15.6 lb, which matters if you will move it between cars or carry it through an airport.

Check your vehicle manual for lower anchor positions and any head-restraint rules.
Rear-facing seats need front-seat room: try the install behind the driver before you commit.
Not certified for aircraft use: plan on gate-checking it or using a different seat to fly.

What features does the AACE booster seat have?

Converts high-back to backless
Lower anchor connectors
8 recline positions in high-back mode (with lower anchors)
9-position headrest
3 seat depth positions
Side impact protection pods
Belt positioner

Colors listed in the US

Caviar, Cedar, Edgehill, Edgehill Blue, Granite, Lake.

What to know before you live with it

Vehicle belts and lower anchors

The AACE must go in a rear seat with a 3-point lap and shoulder belt. The manual rules out lap-only belts, motorized shoulder belts and belts attached to the door or a track. The rigid lower anchor connectors attach only at standard 11 in spacing, show green when locked, and never restrain the child; they secure the booster and enable the recline in high-back mode. Without them, the back of the booster must fit tightly against the vehicle seat, and the front must not hang over the edge.

Source: Nuna AACE manual (PDF)

Fitting the high-back booster

Raise the head support until its bottom is even with the top of the child's shoulders. There are 9 positions, and the sides move outward as it rises. The shoulder belt runs through the red shoulder belt guide and across the chest. The lap belt passes under the armrest, low on the pelvis and snug across the thighs, never over the armrest. The side impact pods should be opened whenever the booster is in a vehicle, and the seat bottom has 3 depth positions.

Source: Nuna AACE manual (PDF)

Backless mode

For children at least 5 years old and 50 to 120 lb, the back comes off by reversing the assembly steps. It can be installed with or without the rigid lower anchors, and it does not recline. The belt runs through the red path under the armrest. If the shoulder belt falls outside the marked zone, use the shoulder belt positioning clip, which attaches on either side. The manual says the top of the child's ears must be at or below the top of the vehicle seat back or headrest.

Source: Nuna AACE manual (PDF)

Removing the covers

Take out the cup holder, release the seat bottom fabric from 3 plastic attachments and open 8 snaps. The seat back cover comes off by opening 2 snaps and unhooking 4 elastic bands; the head support cover unhooks with 4 more once raised. The manual warns not to damage the energy-absorbing foam. Washing and drying follow the care label. The shell is cleaned with only mild detergent, water and a soft cloth, then air dried. Stop using the seat if any part is torn, broken or missing.

Source: Nuna AACE manual (PDF)

Is the AACE booster seat recalled?

No campaign in the current NHTSA child-restraint data names this model family, and I have not run a separate review for it. Check your seat’s model number and date of manufacture before use.

NHTSA recall search · Recent car seat recalls

AACE booster seat: common questions

What are the Nuna AACE weight and height limits?

High-back mode is 40 to 110 lb and 43 to 60 in, for a child at least 4 years old. Backless mode is 50 to 120 lb and 43 to 60 in, for a child at least 5 years old.

Nuna AACE manual (PDF) (opens in a new tab)

Can the AACE be used on an airplane?

No. The manual says it is not certified for aircraft use, because aircraft belts are lap belts only.

Nuna AACE manual (PDF) (opens in a new tab)

Do the AACE lower anchors hold my child?

No. The manual says the rigid lower anchor attachments only secure the booster and allow the recline in high-back mode. The child is always restrained by the vehicle lap and shoulder belt.

Nuna AACE manual (PDF) (opens in a new tab)

When does the AACE booster expire?

The manual says not to use it if it is more than 10 years old. Check the label or stamped do-not-use-after date on the bottom.

Nuna AACE manual (PDF) (opens in a new tab)

How big and heavy is the AACE?

Nuna lists 15.6 lb. In high-back mode it measures 15 in long, 22.5 in wide and 33 in high at its highest, and 14.6 in long, 21.5 in wide and 26 in high at its lowest.

Nuna AACE product page (opens in a new tab)

How does the AACE compare with the LUMN in booster mode?

Nuna's LUMN page lists booster mode for children at least 40 lb up to 110 lb and between 43 and 57 in tall. The LUMN also has a harness mode, which the AACE does not.

Nuna LUMN product page (opens in a new tab)

Answers refer to the model and manual version on this page. Check the instructions supplied with your seat.

Before you buy

Weigh and measure your child. The limits above are the manufacturer’s, and a child has to meet all of them for the mode they will use.
Confirm the exact version. Colors, retail exclusives and model numbers change limits more often than you would expect; Nuna lists 6 colors of this seat.
Read the manual before you buy, not after. It is linked above and holds the fit rules, the install methods and the expiry.
Check recalls by model number and date of manufacture, and register the seat with Nuna so you hear about the next one.