American gives hard-sided carriers the most generous published limit of any major — 19" x 13" x 9" — but for soft-sided carriers the rule is simpler and stricter: it must fit completely under the seat in front of you, period. And American's in-cabin pet fee runs higher than most, so get the carrier right the first time.
American's in-cabin carrier rules
- Hard-sided: up to 19" x 13" x 9"
- Soft-sided: must fit under the seat (the 18" x 11" x 11" standard is the safe target)
- Your pet must be able to stand, turn around, and lie down naturally
- Plan on $125–$150 each way — American has been at the top of the fee range; confirm when you book
- The carrier stays under the seat for taxi, takeoff, and landing
Hard vs soft on American
That 19 x 13 x 9 hard-side allowance looks tempting on paper. In practice, a rigid 9-inch-tall box either fits your aircraft's under-seat clearance or it doesn't — there's no give. A soft-sided carrier at the 18 x 11 x 11 standard compresses to handle the variation between a 737 and a regional jet. Unless you have a specific reason for hard-sided, soft wins on American the same way it wins everywhere else.
What to buy for an American flight
Everything in our travel collection is soft-sided or compressible:
- Rover Ready Expandable Carrier — under-seat compliant closed, expands during layovers at DFW or Charlotte where American connections run long
- Mr. Peanut's Gold Series V3.0 — structured but flexible, built to the soft-sided standard
Before you fly American with your dog
- Measure first — our size guide covers length and standing height
- Add your pet to the reservation early; in-cabin slots are capped per flight
- Confirm the current pet fee — American's has moved more than most airlines'
- Pack leak-proof liner pads plus a spare for the connection
Airline rules change. This reflects American's published guidance as of June 2026 — confirm current requirements with American before you fly. The airline has the final word.
