Airline crate size calculator
Measure your dog or cat, and this calculator works out the minimum inside size IATA’s formula gives for its travel crate. Then it sets out what to do with that number when you buy or hire a crate for a pet flying as checked baggage or as cargo.
The inside of the crate has to clear your pet, and the outside has to suit the airline and the aircraft. The calculator works out the first and tells you what to ask about the second.
Some airlines do not carry pets in the hold at all, so check the section below the calculator before you buy a crate.
A pet flying in the cabin travels in a carrier under the seat in front of you instead. Our pet carrier size checker sets IATA’s minimum for your dog or cat beside the under-seat limits that US and Canadian airlines publish.
Your result appears here: the minimum inside size for your pet’s crate, how it was worked out, and its source.
Check that your airline carries pets in the hold
Before you buy a crate, check that the airline you plan to fly takes pets outside the cabin.
Southwest says no pets are transported in its cargo compartment. JetBlue says it does not book dogs or cats in cargo, only in the cabin. Allegiant says pets are not transported in its cargo area. Avelo says it will not allow pets in the cargo bin. Porter says pets are not permitted in the baggage hold of any of its flights. Frontier says it does not allow pets to be checked as baggage.
American accepts checked pets only for active-duty US military and US State Department Foreign Service personnel on official orders. American Airlines Cargo carries pets that qualify neither for the cabin nor as checked baggage through its PetEmbark service. Delta ships pets only for active US military and State Department Foreign Service personnel with permanent change of station orders.
We read these pages on September 15 and 16, 2026. A policy can change after it is read, so confirm with the airline before you buy.
How the calculator works out the size
IATA publishes a formula for the minimum inside size of a container for one dog or cat, on its Traveler’s Pet Corner page. It takes four measurements from the animal standing and turns them into the three inside dimensions of the crate.
- Inside length = A + ½ B
- Inside width = C × 2
- Inside height = D + bedding
- Snub-nosed breeds: a container 10% larger
Source: IATA, Traveler’s Pet Corner, read September 16, 2026.
IATA says the calculated dimensions are internal container dimensions, and offers the formula to assist in working out the approximate size of a container. It says airlines use these indications to ensure the animal has enough space to turn about normally while standing, to stand and sit erect, and to lie in a natural position.
The formula is for one animal. For two animals sharing a container, IATA gives the width as three times the width across the shoulders, and for three animals, four times, with every measurement taken from the largest animal. It also limits which animals may share, which the crate size formula guide covers.
Work it out by hand
The two tables hold the calculation the calculator runs, so you can do it with a tape measure and a pencil.
| Measurement | What to measure |
|---|---|
| A | From the tip of the nose to the base of the tail |
| B | Height from the ground to the elbow joint |
| C | Width across the shoulders or the widest point, whichever is greater |
| D | Height of the animal in a natural standing position, from the top of the head or the ear tip, whichever is higher, to the floor |
For a dog measuring 24 inches for A, 12 inches for B, 9 inches for C and 20 inches for D, with 1 inch of bedding:
| Inside dimension | IATA’s formula | Worked example |
|---|---|---|
| Length | A + ½ B | 24 + 6 = 30 inches |
| Width | C × 2 | 9 × 2 = 18 inches |
| Height | D + bedding | 20 + 1 = 21 inches |
| Snub-nosed breed | Each of the three 10% larger, as the calculator reads it | 33 by 19.8 by 23.1 inches |
These are the smallest the inside can be. The crate you buy has to be larger inside than all three.
Inside the crate and outside it
IATA’s figures are for the inside of the crate. The walls, the door, the rim where the top and bottom halves meet and any handles all sit outside that space, so a crate always measures more outside than in.
That gap matters in both directions. The inside has to clear your pet, so buy by the inside measurements. The outside has to suit the airline and the aircraft, because the whole crate has to fit into the hold, so check the outside measurements, and the weight with your pet inside, against the limits the airline or cargo service gives you for your route.
Choosing a crate with the number
The calculator gives measurements, not a crate size class or a model, so compare its figures with the inside measurements of the crate you are considering, from its maker or from your own tape measure.
Size is one part of what a travel crate has to meet. It also has to be built to the container requirements in the IATA Live Animals Regulations, which our airline crate requirements guide sets out. Our crate size formula guide takes you through the sizing with a worked example in centimeters.
If you would rather hand the planning to someone, our pet transport service can plan the route, the crate and the paperwork with you. For what a move costs, our pet shipping cost guide breaks down each part.
On our Canadian site, the airline crate requirements guide for pets flying from Canada and the crate size guide for Canada cover the crate rules Air Canada and WestJet Cargo publish, and our Canadian pet transport service plans moves from Canada.
Frequently asked questions
What size crate does my dog need to fly?
IATA’s formula gives the minimum inside size: the length is nose to base of tail plus half the height to the elbow, the width is twice the width across the shoulders or the widest point, and the height is standing height plus bedding, with a 10% larger container for a snub-nosed breed. The crate has to be larger inside than that in every direction, and its outside and its weight have to suit the limits the airline gives you for your route.
Are crate sizes measured inside or outside?
IATA’s formula gives inside dimensions. The walls, door, rim and handles make a crate larger outside than in, and the whole crate has to fit into the hold, so you need both figures: the inside to clear your pet, and the outside for the airline and the aircraft.
Can I buy a crate that matches the calculator’s figures exactly?
No. The crate has to be larger inside than the figures in every direction. The height figure is standing height plus bedding, so a crate that matches it puts your pet’s head or ears against the roof, and IATA offers the formula to work out the approximate size of a container.
Does the calculator tell me which crate size or model to buy?
No. It gives inside measurements and matches them to no size class or model, so compare them with the inside measurements of the crate you are considering, from its maker or from your own tape measure.
Does IATA approve travel crates?
IATA says it does not certify, approve, sell or otherwise endorse any commercial dog or cat travel or shipping container as compliant with the Live Animals Regulations, and that it provides the standards for those containers in Container Requirement 1. Our airline crate requirements guide sets out what a crate has to meet.
How does the snub-nosed setting change the result?
IATA’s pet page, read September 16, 2026, asks for a container 10% larger for a snub-nosed breed and does not say which measurement that applies to. It names boxers, pugs, bulldogs and Pekingese as snub-nosed dogs. The calculator applies the 10% to the length, the width and the height, as the cautious reading.
Can two pets share one crate?
The calculator works out a crate for one animal. For two animals sharing, IATA gives the width as three times the width across the shoulders, and for three animals four times, with every measurement taken from the largest animal, and it limits which animals may share. The crate size formula guide covers sharing.
Can I use this calculator for a pet flying in the cabin?
It works out the same minimum, but a cabin carrier also has to fit under the seat. Our pet carrier size checker sets IATA’s minimum for your dog or cat beside the under-seat limits that US and Canadian airlines publish.