In-cabin pet carriers that fit Allegiant Air
The carriers from our list that clear Allegiant Air's official 18 × 12 × 11 in under-seat limit — sorted best-fit first, with the ones that squeeze in when collapsed flagged.
Short answer: 13 of the 15 carriers we track fit Allegiant Air's 18 × 12 × 11 in limit: 5 with room to spare on every side, 6 with no room to spare on at least one side and 2 only when collapsed or squeezed a little. 2 are too big.
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| Carrier | Size | Fit | Buy |
|---|---|---|---|
Sherpa Original Deluxe (Small) up to ~8 lb · max pet 13″ long × 7.5″ tall 15 × 10 × 8.5 in is within 18 × 12 × 11 in — 3" spare on length, 2" on width, 2.5" on height. · collapsible/flex | 15 × 10 × 8.5 in | Fits | See on Amazon → |
 Mr. Peanut's Gold Series Mini (Low-Profile) up to ~15 lb 17 × 11 × 9 in is within 18 × 12 × 11 in — 1" spare on length, 1" on width, 2" on height. · collapsible/flex | 17 × 11 × 9 in | Fits | See on Amazon → |
Petmate Soft-Sided Kennel Cab (Medium) up to ~10 lb 17 × 10 × 10 in is within 18 × 12 × 11 in — 1" spare on length, 2" on width, 1" on height. | 17 × 10 × 10 in | Fits | See on Amazon → |
Sherpa Original Deluxe (Medium) up to ~16 lb · max pet 16″ long × 9.5″ tall 17 × 11 × 10.5 in is within 18 × 12 × 11 in — 1" spare on length, 1" on width, 0.5" on height. Tightest margin is 0.5", so measure before you fly. · collapsible/flex | 17 × 11 × 10.5 in | Fits | See on Amazon → |
Sleepypod Atom up to ~12 lb 17 × 8.5 × 10.5 in is within 18 × 12 × 11 in — 1" spare on length, 3.5" on width, 0.5" on height. Tightest margin is 0.5", so measure before you fly. | 17 × 8.5 × 10.5 in | Fits | See on Amazon → |
Mr. Peanut's Gold Series Standard (Expandable) up to ~20 lb 18 × 11 × 10 in is within 18 × 12 × 11 in — 0" spare on length, 1" on width, 1" on height. Tightest margin is 0", so measure before you fly. · collapsible/flex | 18 × 11 × 10 in | Exact fit | See on Amazon → |
Diggs Passenger pet size not published · Diggs discontinued this carrier — link goes to similar carriers 17 × 12 × 10.5 in is within 18 × 12 × 11 in — 1" spare on length, 0" on width, 0.5" on height. Tightest margin is 0", so measure before you fly. | 17 × 12 × 10.5 in | Exact fit | Search Amazon → |
ibiyaya JetPaw Expandable Backpack up to ~17 lb 18 × 12 × 10.5 in is within 18 × 12 × 11 in — 0" spare on length, 0" on width, 0.5" on height. Tightest margin is 0", so measure before you fly. | 18 × 12 × 10.5 in | Exact fit | See on Amazon → |
Petsfit (Medium) Expandable Soft-Sided up to ~13 lb 17 × 11 × 11 in is within 18 × 12 × 11 in — 1" spare on length, 1" on width, 0" on height. Tightest margin is 0", so measure before you fly. | 17 × 11 × 11 in | Exact fit | See on Amazon → |
Bergan Comfort Carrier (Small) pet size not published 16 × 8 × 11 in is within 18 × 12 × 11 in — 2" spare on length, 4" on width, 0" on height. Tightest margin is 0", so measure before you fly. | 16 × 8 × 11 in | Exact fit | See on Amazon → |
Frisco Premium Airline-Compliant Carrier up to ~22 lb 18 × 11 × 11 in is within 18 × 12 × 11 in — 0" spare on length, 1" on width, 0" on height. Tightest margin is 0", so measure before you fly. | 18 × 11 × 11 in | Exact fit | Search Amazon → |
Sleepypod Air up to ~18 lb Collapses from 22" to ~16" long, which fits — height 10.5" is within 11". · collapsible/flex | 22 × 10.5 × 10.5 in | Fits collapsed | See on Amazon → |
SturdiBag Pro (Large, Flexible Height) pet size not published 11.5" tall vs a 11" limit — 0.5" over, but the flexible-height top compresses down. Verify it squeezes under your actual seat. · collapsible/flex | 18 × 11.5 × 11.5 in | Flexes — 0.5" over | See on Amazon → |
Every fit is against the published maximum; real under-seat space varies by aircraft (why). Full rules & fees: Allegiant Air pet policy → · how Allegiant Air ranks on fee and space →
Other airlines: American Airlines · American Eagle (regional, incl. Republic Airways) · Asiana Airlines · Austrian Airlines · Avelo Airlines · Avianca
Common questions
What size pet carrier does Allegiant Air allow in the cabin?
Allegiant Air's published limit for a carrier under the seat in front of you is 18 × 12 × 11 in. Weight limit: not published. We last checked this against Allegiant Air's own pet policy on 2026-09-24.
How many pet carriers fit Allegiant Air's limit?
13 of the 15 carriers we track fit Allegiant Air's 18 × 12 × 11 in limit: 5 with room to spare on every side, 6 with no room to spare on at least one side and 2 only when collapsed or squeezed a little. 2 are too big.
Which carriers only fit Allegiant Air when collapsed or squeezed?
Sleepypod Air, SturdiBag Pro (Large, Flexible Height). Each is over the published size until folded or pressed down, so measure yours and expect it may be checked at the gate.
Which carriers are too big for Allegiant Air?
Away The Pet Carrier, Sherpa Original Deluxe (Large). Each is over the 18 × 12 × 11 in limit.
How much does Allegiant Air charge for a pet in the cabin?
$50 per segment, per carrier. Confirm the current fee with Allegiant Air when you book.