Flying
IATA crate size: how to choose the right crate
A crate that is too small is refused at check-in; one that is too big adds weight and lets your pet slide around. IATA gives a simple method: four measurements taken on your pet standing up, and a formula for the minimum internal dimensions. Here is how to use it, with a worked example.
Updated · official sources at the bottom of the page
The four measurements: A, B, C and D
Measure your pet standing naturally on a flat floor, with a soft tape measure. It helps to have two people, one to hold the animal and one to measure. The definitions come from Container Requirement 1 of IATA's Live Animals Regulations (52nd edition, January 2026).
| Measurement | What you measure | Common slip |
|---|---|---|
| A | Length from the tip of the nose to the base (root) of the tail | Measuring to the end of the tail |
| B | Height from the ground to the elbow joint | Measuring to the shoulder instead |
| C | Width across the shoulders, or at the widest point if that is wider | On a stocky dog the chest may be wider than the shoulders |
| D | Standing height from the floor to the top of the head or the ear tips, whichever is higher | Leaving out erect ears, or measuring the dog sitting |
For a puppy that is still growing, measure as close to departure as you can and leave some margin: what counts is its size on the day it flies.
IATA's formula
The results are minimum internal dimensions for a single animal:
- Internal length = A + ½ B
- Internal width = C × 2
- Internal height = D + bedding depth
Two points in IATA's text matter as much as the formula itself:
- The formula is only a guide. The mandatory requirement is that the animal can stand, sit erect, lie in a natural position and turn around normally while standing. If the formula gives a crate where that is not possible, go bigger.
- Snub-nosed breeds need a crate 10% larger. IATA does not say exactly how to apply the 10%; in practice each of the three internal dimensions is increased. The AVMA, for its part, advises one size larger than normal. Some airlines have their own rule, which we check for your flight.
A worked example
Two medium-sized dogs, with 3 cm of bedding on the crate floor:
| Step | Border Collie type | Snub-nosed dog (bulldog type) |
|---|---|---|
| Measurements | A = 75 cm, B = 30 cm, C = 22 cm, D = 58 cm | A = 60 cm, B = 22 cm, C = 28 cm, D = 45 cm |
| Length | 75 + 15 = 90 cm | 60 + 11 = 71 cm |
| Width | 22 × 2 = 44 cm | 28 × 2 = 56 cm |
| Height | 58 + 3 = 61 cm | 45 + 3 = 48 cm |
| Uplift | — | +10%: 71 × 1.1 = 78.1; 56 × 1.1 = 61.6; 48 × 1.1 = 52.8 |
| Minimum inside | 90 × 44 × 61 cm | 79 × 62 × 53 cm (rounded up to the next centimetre) |
Then compare with the crate's internal dimensions, not the external ones the manufacturer advertises: wall thickness, the door grille and the curved roof of many plastic crates all eat into usable space. Manufacturers' size names ("400", "500", "XL" and so on) are not IATA sizes. If in doubt, measure the inside yourself, taking height at the lowest point of the roof above your pet's head.
Weight matters too. Airlines set their limits on the animal's weight with its crate: Air France, for example, takes dogs in the hold up to 75 kg including the crate. Above 60 kg in total, IATA requires forklift spacers at least 5 cm high under the crate.
Work out the minimum internal crate size
Measure your pet standing, in centimetres, then compare the result with the crate's internal dimensions.
Indicative calculation following IATA's rule (length A + ½B, width C × 2, height D + bedding). Your pet must be able to stand, sit, lie down and turn around: if not, go bigger. The airline may have its own requirements.
Materials, ventilation, door and bolts
A crate of the right size can still be turned away if it is not built to standard. What IATA requires for dogs and cats in the hold:
- Materials: fibreglass, metal, rigid plastic, welded mesh, solid wood or plywood. Crates made entirely of wire mesh are not allowed. Rigid plastic suits most dogs, but not necessarily very large or aggressive dogs, and the airline has the final say.
- Assembly: the two halves of a plastic crate must be securely bolted together; plastic clips alone are not enough, and IATA recommends a metal nut and bolt in every hole.
- Door: the whole of one end, sliding or hinged; locking pins must engage the crate by at least 1.6 cm; metal hinges and pins on a plastic door; cable ties at the four corners of the door frame.
- Ventilation: at least 16% of the surface of the four sides, on all four sides, in the upper two-thirds for the sides and back; one end fully meshed (the door can be that end).
- Openings: no larger than 25 × 25 mm for a dog and 19 × 19 mm for a cat, so neither nose nor paws can get through; mesh at least 2.5 mm thick for dogs, 2.0 mm for cats.
- Everything else: smooth interior with nothing to bite or scratch; solid, leak-proof floor; spacers along both long sides and the back so other baggage cannot block the vents; handles; wheels removed or made inoperable.
IATA does not certify, approve or endorse any crate brand, so a crate sold as "IATA approved" still needs checking point by point. Airlines can also be stricter: Air France only accepts rigid plastic or fibreglass crates, bolted together, in the hold. Each airline's conditions and the largest crates they take are covered on our airline pet crates page.
Bowls, bedding and labels
- Water: an open bowl fixed inside, which can be filled from outside without opening the door. Drip bottles and dispensers do not replace it.
- Food: a container inside or attached to the crate, and a little food attached to the outside in case of delays.
- Bedding: absorbent material suited to the species. The AVMA advises against thick blankets and fluffy towels a pet could bury its nose in: a thin blanket or flat newspaper is enough.
- Labels: the green "Live Animals" label is mandatory, and so are "This Way Up" labels on at least two opposite sides. Marking your pet's name is recommended; add your contact details and those of the person collecting.
- Seals: some countries require the crate to be sealed in transit, so it must be possible to seal it.
Two pets in one crate?
Only in limited cases. Width becomes C × 3 for two animals and C × 4 for three, using the measurements of the largest. IATA only allows two adults of comparable size, up to 14 kg each and used to living together, or up to three weaned puppies or kittens no older than six months and no heavier than 14 kg each. Any animal over 14 kg travels alone. Some national rules and airlines require one crate per animal, so check before you buy.
Common mistakes
- Choosing from external dimensions or the manufacturer's size name.
- Measuring the dog sitting down, or leaving erect ears out of the height.
- Forgetting the bedding in the height.
- Skipping the uplift for a snub-nosed breed.
- Keeping plastic clips instead of bolts, or working wheels.
- Swapping the bowl for a drip bottle.
- Buying the crate the day before: your pet needs weeks to get used to it. See preparing your pet for a long-haul flight.
Frequently asked questions
Is a crate bigger than the minimum better?
Not necessarily. Beyond a few centimetres of margin, a bigger crate weighs more, may exceed what the airline or the aircraft hold accepts, and lets your pet slide about during handling. Aim for the calculated minimum, adjusted so your pet can stand and turn around comfortably.
Do these rules apply to a cabin carrier?
Partly. IATA exempts cabin containers from being rigid and from spacers and bowls, but they must still let the animal stand and turn around, be ventilated and leak-proof, and carry a "Live Animals" label. The maximum size is set by the airline.
My dog falls between two sizes. Which should I choose?
The larger one, provided it is within the airline's limits. A crate that is too tight is refused at the desk, and finding another one at the airport on departure day is rarely easy.
Official sources
The rules above come from the texts and pages of these authorities. Last checked: .
- IATA — Live Animals Regulations, Container Requirement 1 (52e édition, janvier 2026)
- IATA — Traveler’s Pet Corner
- AVMA — Traveling with your dog or cat
- AVMA — Air travel and short-nosed dogs FAQ
- Air France — Voyager avec des animaux de compagnie (caisses acceptées en soute ; page mise à jour le 9 septembre 2026)
Rules change. Before anything is booked, we reconfirm every requirement with the authorities, the airline and the vet for your pet and your itinerary.
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