BudgetPlan your spendHospital bagFree checklist

Britax Marathon ClickTight

The Britax Marathon ClickTight rear-faces up to 40 lb, forward-faces up to 65 lb, and is 18.5 in wide, per Britax. A convertible seat that rear-faces to 40 lb and forward-faces to 65 lb, installed with Britax's ClickTight belt-lock system.

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

  • $299.99List price
  • 40 lbRear-facing to
  • 65 lbHarness to
  • 28.5 lbSeat weight
See it on Britax's site

When does it expire?

Follow Britax

All convertible car seats

Marathon ClickTight: key facts

  • The Britax Marathon ClickTight rear-faces from 5 to 40 lb and up to 49 in tall; forward-faces with a harness from 20 to 65 lb and up to 49 in tall, per Britax.
  • Outgrown by height: "Rear-facing: when the top of the child's head is at least 1 in. (2.5 cm) below the top of the head restraint/pad. Forward-facing: when the top of the ears are below the top of the head restraint/pad."
  • It installs with ClickTight (seat belt).
  • Britax says it expires 10 years after the date of manufacture.
  • Britax lists it as certified for aircraft ("This child seat is certified for aircraft use.").
  • It's 18.5 in wide at the widest point and weighs 28.5 lb.

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

How the Marathon ClickTight stacks up

Against the 40 convertible car seats we track. The shaded band is where the middle half of them fall; the dot is this one.

Expiration10 years

Within the typical range for convertible car seats (9 years to 10 years).

This one
7 yearsmiddle 10 years10 years
Rear-facing limit40 lb18th highest rear-facing limit of 39

Within the typical range for convertible car seats (40 lb to 50 lb).

This one
35 lbmiddle 40 lb65 lb
Forward-facing limit65 lbHighest forward-facing limit of 39 convertible car seats

The same as most convertible car seats (65 lb).

This one
40 lbmiddle 65 lb65 lb
Width18.5 in19th narrowest of 29

Within the typical range for convertible car seats (17 in to 18.9 in).

This one
14.5 inmiddle 17.8 in23.5 in
Weight28.5 lb23rd lightest of 26

Above the typical range for convertible car seats (21.6 lb to 28 lb).

This one
8 lbmiddle 26 lb31.3 lb
Price$299.9915th lowest price of 38

Within the typical range for convertible car seats ($129.99 to $499.99).

This one
$59.99middle $399.99$990

Flying with the Marathon ClickTight

Britax's label: “This child seat is certified for aircraft use.” It is 18.5 in wide at its widest point.

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

  • ClickTight installation
  • 14 harness positions
  • Rear-facing to 40 lb

Worth checking

  • Heavy at 28.5 lb
  • No booster mode
  • 18.5 in wide

Where to buy the Marathon ClickTight

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

Britax Marathon ClickTight
TypeConvertible
List price$299.99
Rear-facing weight5–40 lb
Rear-facing heightUp to 49 in
Forward-facing weight20–65 lb
Forward-facing heightUp to 49 in
Seat weight28.5 lb
Width18.5 in
Head ruleRear-facing: when the top of the child's head is at least 1 in. (2.5 cm) below the top of the head restraint/pad. Forward-facing: when the top of the ears are below the top of the head restraint/pad.
InstallationClickTight (seat belt)
Load legNo
RotatesNo
Harness heights14
Aircraft labelCertified for aircraft, per the maker
No added flame retardantsYes
Expires after10 years

Compare the Marathon ClickTight with

How each closest rival differs from the Marathon ClickTight, from the makers' specs.

Ask the meadow

Marathon ClickTight: questions answered

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

Does the Britax Marathon ClickTight rear-face longer than other convertible seats?

20 of the 50 convertible seats we track rear-face to a higher weight than its 40 lb. The highest is the Axkid One 3 at 65 lb. NHTSA: stay rear-facing "until he or she reaches the top height or weight limit allowed by your car seat's manufacturer." (NHTSA)

Will the Britax Marathon ClickTight fit three across or in a small car?

It's wider than 68% of the convertible seats we track, at 18.5 in. The narrowest is the WAYB Pico at 14.5 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 Britax Marathon ClickTight on a plane?

Yes, Britax lists it as certified for aircraft; look for the red-lettered label that says so. The FAA asks that a car seat go in a window seat so it doesn't block the aisle, and the crew will look for that label. It weighs 28.5 lb to carry through the airport.

Marathon ClickTight or Chili Spin SI: what's different?

By the makers' specs, the Marathon ClickTight has no added flame retardants (maker's claim); the Chili Spin SI has an anti-rebound bar; the Chili Spin SI has a rotating seat; the Marathon ClickTight lists for $40 less. See every spec side by side.

Is it OK to buy a used Marathon ClickTight?

NHTSA publishes guidance on used car seats on its car seat page. Britax lists a lifespan of 10 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 convertible car seats

Where these specs come from

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