The three ways pets fly
When you book a flight with a pet, there are three distinct routes, each with very different rules:
In-cabin (under-seat): Your pet travels in the passenger cabin in an approved soft-sided carrier stowed under the seat in front of you. You pay a one-way pet fee (typically $100–$150 on U.S. airlines). This is the safest option because the pet is with you throughout the flight.
Checked baggage (in the hold, same plane): Your pet travels in a hard-sided IATA-compliant crate in the temperature-controlled hold, on the same flight. Not all airlines offer this — and several have stopped accepting pets as checked baggage entirely.
Cargo (separate booking): Your pet flies as air cargo, usually on a different booking from yours and sometimes on a different flight. This route is used for larger pets or when traveling to destinations that don’t accept pets in the cabin. It is also the most common route for international relocations.
Which route is right for your pet?
Use in-cabin if: Your pet weighs under the airline’s combined (pet + carrier) limit, fits in the carrier dimensions, is not a snub-nosed breed, and you’re flying a route that allows it.
Consider checked baggage if: Your pet is too large for the cabin but you want to travel on the same flight. Note: many airlines no longer offer this — verify before booking.
Plan for cargo if: Your pet is large, brachycephalic restrictions apply to the airline’s cargo program (and your pet is not brachycephalic), you’re relocating internationally, or the destination requires it. Cargo is more regulated than many people assume, but it requires more advance planning.
In-cabin: the rules that matter
Every airline sets its own limits, but the common framework is:
- Weight: The combined weight of your pet and the carrier cannot exceed the airline’s limit — typically 20 lb for U.S. carriers, though some allow up to 25 lb (United Airlines). The carrier is weighed too, so account for it.
- Carrier dimensions: The carrier must fit under the seat in front of you without blocking the aisle or encroaching on the floor space. Typical limits are around 18 × 11 × 9 inches, but they vary by airline and by aircraft type. A soft-sided carrier is almost always required.
- Breed restrictions: No U.S. airline explicitly bans a specific breed from the cabin based on the breed alone, but several prohibit “snub-nosed” or brachycephalic breeds from their cargo programs. For the cabin, the key rule is usually that the pet must be calm, odorless, and able to stand, sit, and turn around in the carrier.
- Number of pets: Typically one pet carrier per passenger, and most airlines cap the total number of in-cabin pets per flight at 4–6.
Use the in-cabin eligibility checker to compare your airline’s limits against your pet’s weight and carrier size.
Cargo: what actually happens
When a pet travels as cargo, the airline or cargo operator places them in a temperature-controlled hold that is pressurized the same as the passenger cabin. Modern cargo holds for live animals maintain appropriate temperature ranges. The International Air Transport Association (IATA) publishes Live Animals Regulations (LAR) that set minimum container size, ventilation, documentation, and handling requirements.
What makes cargo riskier than in-cabin:
- Your pet is out of your sight for the entire journey, including during connections
- Ground delays in hot or cold weather increase temperature-exposure risk
- Crate size errors (too small) cause distress and injury
- Brachycephalic breeds have severely restricted airflow even under normal conditions, which is why most airlines ban them from cargo
Minimizing cargo risk:
- Use an IATA-compliant hard-sided crate that is large enough for your pet to stand, turn, and lie down
- Freeze water so it doesn’t spill during loading
- Do not sedate your pet — veterinary organizations advise against sedation for air travel because sedation impairs a pet’s ability to regulate body temperature and balance
- Book a direct flight whenever possible
- Avoid summer and winter weather extremes — most airlines have temperature embargoes that may ground your pet’s flight
What changes for international flights
For international routes, the destination country’s import rules supersede the airline’s cabin rules. Some countries (notably Singapore, Japan, Australia, and New Zealand) have no in-cabin option — all pets must arrive as cargo and pass through official quarantine. Even when in-cabin is technically allowed, the health certificate requirements are the same as for cargo.
Always look up the destination country’s requirements before you assume in-cabin is possible. The country entry requirements section and the travel readiness checklist tool are good starting points.
Also see the corridor note: if you are traveling with your pet internationally and you yourself need to check visa requirements for your destination, VisaGlance provides a clear breakdown of entry requirements for your nationality — it is worth checking both at the same time.
Before you book: the checklist
- Confirm the airline’s current pet policy on their official website (not a third-party summary)
- Weigh your pet, weigh your carrier, and add the two together
- Measure your carrier when loaded (it’s often slightly smaller than the listed dimensions)
- Check whether your pet’s breed is on any restriction list
- For international travel: check the destination country’s documentation requirements and timeline
- Book early — most airlines limit the number of in-cabin pets per flight and slots fill up
As of the date of this guide. Always confirm requirements with your airline and official authorities before you travel.