For most major airlines the size of Pet Carrier In Cabin averages 22”Lx14”Wx 9” and 8kg or 17lbs for your Pet. Soft-Sided Carriers are best for Airlines. The top compresses 1 or 2 inches, giving you more options than a Hard-Sided carrier. The carrier must be stowed under the seat at least for take-off and landing.
See 4 Best In-Cabin Pet Carriers for Airlines 2022