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In-Cabin Pet Carrier Size: Delta, United, American, and 4 More US Airlines Side by Side
The six soft-sided carrier limits compared
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Airline size limit
Pet carrier limit 18×11×11 in (soft-sided)
18 × 11 × 11 in (457 × 279 × 279 mm)
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Airline size limit
Pet carrier limit 18×14×11 in (soft-sided)
18 × 14 × 11 in (457 × 356 × 279 mm)
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Airline size limit
Pet carrier limit 18×12×11 in (soft-sided)
18 × 12 × 11 in (457 × 305 × 279 mm)
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Airline size limit
Pet carrier limit 18×10.5×10 in (soft-sided)
18 × 10.5 × 10 in (457 × 267 × 254 mm)
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Airline size limit
Pet carrier limit 17×12.5×8.5 in
17 × 12.5 × 8.5 in (432 × 318 × 216 mm)
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Airline size limit
Pet carrier limit 17×11×9.5 in (soft-sided)
17 × 11 × 9.5 in (432 × 279 × 241 mm)
The short answer
- 18×11×11 in (457×279×279 mm)Delta, United, American — three airlines publish the same soft-sided limit; hard-sided limits differ by airline and flight type
- 18×14×11 in (457×356×279 mm)Frontier soft-sided — 3 in wider than the 18×11×11 in limit; hard-sided is 18×14×8 in
- 18×12×11 in (457×305×279 mm)Allegiant soft-sided (18×12×11 in); hard-sided 17×11×10.5 in
- 18×10.5×10 in (457×267×254 mm)Southwest — maximum for other approved carriers; Southwest-branded carrier is 15×10×10 in
- 17×12.5×8.5 in (432×318×216 mm)JetBlue — same limit for both soft and hard-sided; carrier counts as the personal item
- 17×11×9.5 in (432×279×241 mm)Alaska — soft-sided limit; no hard-sided dimensions published
See the sizes in AR (shown as boxes)
The four sizes as boxes at their published dimensions
Preparing 3D…
1 18×11×11 in2 18×14×11 in3 17×12.5×8.5 in4 17×11×9.5 in
On a phone, the "View in your room (AR)" button places the boxes in your room. The boxes are locked to the published dimensions and cannot be resized. They show size only and are not 3D replicas of the products.
Drawn to the same scale
Size limits side by side
| Airline | Soft-sided carrier (L × W × H) | Hard-sided carrier (L × W × H) |
|---|---|---|
| Delta | 18×11×11 in (457×279×279 mm) | Not published on the policy page |
| United | 18×11×11 in (457×279×279 mm) | 17.5×12×9 in (445×305×229 mm) |
| American (AA) | 18×11×11 in (457×279×279 mm) | 19×13×9 in (483×330×229 mm) |
| Southwest | 18×10.5×10 in (457×267×254 mm) | Not published on the policy page |
| JetBlue | 17×12.5×8.5 in (432×318×216 mm) | 17×12.5×8.5 in (432×318×216 mm) |
| Alaska | 17×11×9.5 in (432×279×241 mm) | Not published on the policy page |
| Frontier | 18×14×11 in (457×356×279 mm) | 18×14×8 in (457×356×203 mm) |
| Allegiant | 18×12×11 in (457×305×279 mm) | 17×11×10.5 in (432×279×267 mm) |
Millimeter values converted at 1 in = 25.4 mm and rounded to the nearest whole millimeter. All dimensions are exterior (outside of carrier when fully closed and packed). "Not published" means no specific dimensions appear on the policy page; check with the airline directly. Policies change — verify with your airline before travel. Hawaiian Airlines now shares baggage policy with Alaska Airlines following their merger and is covered by Alaska's entry above. Spirit Airlines ceased operations on 2026-05-02 and is not included.
What the numbers mean
Delta, United, and American publish the same soft-sided limit: 18 × 11 × 11 in. A carrier built to that size passes at all three airlines without adjustment. The 18 in length is the longest side on every airline except JetBlue and Alaska, which set 17 in.
Width is where the biggest gap appears. Frontier allows 14 in wide — 3 in more than the 11 in allowed by Delta, United, and American. Allegiant allows 12 in. Southwest limits other approved carriers to 10.5 in. JetBlue allows 12.5 in but at the shorter 17 in length. A carrier built to the Frontier maximum (18 × 14 × 11 in) exceeds the width limit at Delta, United, American, Southwest, and Alaska, and exceeds the length limit at JetBlue and Alaska.
Height is more consistent. Five of the eight airlines (Delta, United, American, Frontier, Allegiant) set 10 or 11 in for soft-sided carriers. Southwest sets 10 in. JetBlue is the tightest at 8.5 in. Alaska sets 9.5 in.
The carrier that fits the most airlines is one at or under 17 × 11 × 9.5 in (Alaska's soft-sided limit). At those dimensions, the carrier passes Alaska, JetBlue (17 × 12.5 × 8.5 in, all three sides), Delta, United, and American (the 17 in and 9.5 in fit within 18 × 11 × 11 in because 9.5 < 11). It does not fit Southwest's 10.5 in width if the carrier is exactly 11 in wide. The carrier must also physically fit under the seat in front of you; aircraft under-seat space varies by aircraft type and seat row.
Product links
Airline-approved pet carriers 18×11×11 in on Amazon
Airline-approved pet carriers 18×14×11 in on Amazon
Airline-approved pet carriers 18×12×11 in on Amazon
Airline-approved pet carriers 18×10.5×10 in on Amazon
FAQ
What is the standard in-cabin pet carrier size for US airlines?
Delta, United, and American all publish the same soft-sided limit: 18 × 11 × 11 in (457 × 279 × 279 mm). This is the most common soft-sided limit across the seven airlines on this page. Frontier allows a wider carrier at 18 × 14 × 11 in; Allegiant allows 18 × 12 × 11 in; Southwest limits other approved carriers to 18 × 10.5 × 10 in; JetBlue limits all carriers (soft and hard) to 17 × 12.5 × 8.5 in; Alaska limits soft-sided carriers to 17 × 11 × 9.5 in. The carrier must always fit under the seat in front of you. Policies can change — verify with your airline before travel.
Can I use a hard-sided pet carrier in the cabin on US airlines?
JetBlue and Allegiant both accept hard-sided carriers and publish separate dimensions: JetBlue 17 × 12.5 × 8.5 in (same as soft), Allegiant 17 × 11 × 10.5 in. Frontier publishes a smaller hard-sided limit: 18 × 14 × 8 in (3 in shorter than its soft-sided limit). Delta, Southwest, and Alaska do not publish separate hard-sided dimensions. American publishes hard-sided limits for mainline and Eagle flights: 19 × 13 × 9 in and 16 × 12 × 8 in respectively.
Which US airline has the largest in-cabin pet carrier allowance?
Among the seven airlines on this page, Frontier publishes the largest soft-sided limit by volume: 18 × 14 × 11 in (457 × 356 × 279 mm), which is 3 in wider than Delta, United, and American at their 18 × 11 × 11 in limit. Allegiant allows 18 × 12 × 11 in. Alaska and JetBlue have shorter length limits at 17 in versus 18 in for the others.
Does the pet carrier count as a carry-on or personal item?
At JetBlue, the pet carrier counts as your one personal item. At Delta, United, American, Southwest, Alaska, Frontier, and Allegiant, the pet carrier replaces your personal item — you may still bring a carry-on bag. Check each airline's current pet policy before booking, as these rules can change.
See also: Carry-On vs Personal Item Size — nine US airlines' carry-on and personal item limits. Checked Bag Size Limits — nine US airlines' checked bag limits.
Sources
- Delta pet policy: delta.com/us/en/pet-travel/overview (checked 2026-10-05). Delta's policy page states maximum soft-sided carrier dimensions of 18" x 11" x 11" as the size that fits most aircraft types. Hard-sided: no dimensions published on the policy page — Delta states the maximum dimensions depend on the aircraft. Carriers must fit fully under the seat in front of you. Delta does not publish separate hard-sided carrier dimensions.
- United pet policy: united.com/en/us/fly/travel/pets.html (checked 2026-10-05). Soft-sided: 18 × 11 × 11 in. Hard-sided: 17.5 × 12 × 9 in. Carrier must fit under the seat in front of you. Source: united.com pet travel policy (checked via cabinpets.com citing united.com, 2026-09-23).
- American (AA) pet policy: aa.com/web/i18n/travel-info/special-assistance/pets.html (checked 2026-10-05). Soft-sided (all flights): 18 × 11 × 11 in (46 × 28 × 28 cm). Hard-sided (American mainline): 19 × 13 × 9 in (48 × 33 × 22 cm). Hard-sided (American Eagle): 16 × 12 × 8 in (40 × 30 × 20 cm). Source: aa.com traveling with pets (checked via web search citing aa.com, 2026-10-05).
- Southwest pet policy: support.southwest.com/helpcenter/article/What-type-of-pet-carriers-can-I-bring (checked 2026-10-05). "18\" (L) x 10.5\" (W) x 10\" (H)" maximum dimensions for other approved carriers. Southwest also sells its own branded carrier at 15" (L) x 10" (W) x 10" (H). Hard-sided: no dimensions published on the policy page.
- JetBlue pet policy: jetblue.com/help/traveling-with-pets (checked 2026-10-05). "Carriers cannot exceed 17\" L x 12.5\" W x 8.5\" H (43.18 cm L x 31.75 cm W x 21.59 cm H)." Both soft-sided and hard-sided carriers are accepted at the same dimensions.
- Alaska pet policy: alaskaair.com/content/travel-info/pets (checked 2026-10-05). Soft-sided carrier maximum 17" x 11" x 9.5". Hard-sided: no dimensions published on the policy page. Source: alaskaair.com traveling with pets (checked via search result citing alaskaair.com, 2026-10-05).
- Frontier pet policy: faq.flyfrontier.com/help/do-you-allow-pets-on-the-plane (checked 2026-10-05). "Max size (soft-sided): 18\" L x 14\" W x 11\" H." "Max size (hard-sided): 18\" L x 14\" W x 8\" H." Carrier must fit under the seat in front of you.
- Allegiant pet policy: allegiantair.com/contract-carriage (checked 2026-10-05). Article 47: "All soft-sided pet carriers may not exceed external dimensions of eighteen inches by twelve inches by eleven inches (18 in. X 12 in. X 11 in.) when fully closed." "All hard-sided pet carriers may not exceed external dimensions of seventeen inches by eleven inches by ten and a half inches (17 in. X 11 in. X 10.5 in.) when fully closed."
- Credit card reference: ISO/IEC 7810 ID-1, 85.60×53.98 mm (rounded to 85.6×54 mm in the figure caption).
- Hawaiian Airlines: per the Alaska Airlines pet policy page (alaskaair.com), Hawaiian Airlines and Alaska Airlines share baggage and pet policies following their merger. Hawaiian is covered by the Alaska entry above.
- Spirit Airlines: ceased operations on 2026-05-02 and is not included.