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Diono Monterey 4DXT

The Diono Monterey 4DXT is 20.5 in wide, weighs 18.3 lb, and has a booster weight limit of 120 lb, per Diono.

DiscontinuedNo longer made or sold new. Specs are kept for comparing generations.

  • $199.99List price
  • 120 lbBooster to
  • 18.3 lbSeat weight
  • 20.5 inWidth
See it on Diono's site

When does it expire?

All booster seats

Monterey 4DXT: key facts

  • The Diono Monterey 4DXT works as a booster from 40 to 120 lb and 38 to 63 in tall, per Diono.
  • It installs with automotive steel LATCH connectors with two easy-ad.
  • Diono says it expires 8 years after the date of manufacture.
  • Diono says it isn't certified for aircraft.
  • It's 20.5 in wide at the widest point and weighs 18.3 lb.

From Diono's manual and published specs. Always follow the limits on your seat's labels.

How the Monterey 4DXT stacks up

Against the 66 booster seats we track. The shaded band is where the middle half of them fall; the dot is this one.

Booster weight limit120 lbHighest booster limit of 65 booster seats

Within the typical range for booster seats (100 lb to 120 lb).

This one
100 lbmiddle 110 lb120 lb
Expiration8 years

Within the typical range for booster seats (8 years to 10 years).

This one
6 yearsmiddle 10 years12 years
Width20.5 in30th narrowest of 32

Above the typical range for booster seats (17 in to 18.6 in).

This one
10.2 inmiddle 17.5 in23.2 in
Weight18.3 lb40th lightest of 43

Above the typical range for booster seats (6 lb to 14 lb).

This one
1.8 lbmiddle 9.8 lb20.9 lb
Price$199.9942nd lowest price of 54

Above the typical range for booster seats ($55.99 to $186.99).

This one
$19.98middle $99.99$399.99

Flying with the Monterey 4DXT

Diono's label: “Diono booster seats are not meant to be used on airplane.” American lists “Booster seats with no approval label or shoulder harness” under seats and devices not approved for use on board (source).

What airlines say about car seats:

  • American: “Each ticketed customer is allowed 1 stroller and 1 car seat to be checked free of charge” “If an unoccupied, adjoining seat is not available, the gate agent will check the safety seat to your final destination.” Source
  • Alaska: “We will transport your child's car seat and stroller free of charge as checked baggage.” Source
  • JetBlue: “Checking a child safety seat will not count towards your checked baggage allowance and there is no fee assessed” Source
  • Spirit: “One (1) car seat will be accepted per child as checked baggage at no charge.” Source
  • Frontier: “strollers and car seats can be checked for free.” Source
  • Allegiant: “There is no charge for checking or gate checking one car seat per fare-paying passenger.” Source
  • Breeze: “Child seats may be carried on board the aircraft if a seat has been purchased for the Infant or Child” Source

Quoted from each airline's page as of 2026-11-02.

Listed features

  • Maker lists automotive steel LATCH connectors and two easy-adjust LATCH straps
  • Maker lists an 11-position headrest and a backrest that expands up to 6.5 in (16.5 cm)
  • Converts to backless booster with detachable back per maker

Worth checking

  • Maker states Diono booster seats are not meant to be used on airplane

Where to buy the Monterey 4DXT

Prices and availability change. We may earn a commission from some links.

good to know
  • Discontinued. You may still find it used or on clearance.
  • Check for recalls: Search the agency's recall list with the model number and date code from the label: NHTSA recall search.
  • Car seat use and installation: see NHTSA's car seat page, which also lists free car seat inspection by certified technicians. Check the label and the maker's instructions, and ask your pediatrician about your child.

Full specs

Diono Monterey 4DXT
TypeBooster
List price$199.99
Booster weight40–120 lb
Booster height38–63 in
Seat weight18.3 lb
Width20.5 in
Installationautomotive steel LATCH connectors with two easy-ad
Aircraft labelNot certified for aircraft
Expires after8 years

Compare the Monterey 4DXT with

How each closest rival differs from the Monterey 4DXT, from the makers' specs.

Ask the meadow

Monterey 4DXT: questions answered

From Diono's published specs, last checked 2026-11-06.

Will the Diono Monterey 4DXT fit three across or in a small car?

It's wider than 94% of the boosters we track, at 20.5 in. The narrowest is the Mifold Comfort Grab-and-Go Booster at 10.2 in. Fit depends on your vehicle; check each seat's manual and your vehicle manual. Car seat use and installation: see NHTSA's car seat page, which also lists free car seat inspection by certified technicians. Check the label and the maker's instructions, and ask your pediatrician about your child.

Can you bring the Diono Monterey 4DXT on a plane?

Diono doesn't list it as certified for aircraft, so it can be checked as luggage but not used in the plane seat. See seats approved for planes.

Is it OK to buy a used Monterey 4DXT?

NHTSA publishes guidance on used car seats on its car seat page. Diono lists a lifespan of 8 years from manufacture for this model. Check the label and the maker's instructions, and ask your pediatrician about your child.

Still wondering? Write to us at hello@cribpicks.com and we'll look it up.

More booster seats

Where these specs come from

Last checked 2026-11-06. Spot something wrong? Tell us. Read our editorial and safety policy and corrections.