What crate size does a labrador need?

Measure yours, but as an order of magnitude: A = 90 cm, B = 38, C = 28, D = 62 gives a required interior of 109 × 56 × 62 cm, which is a US series 700 or a Ferplast Atlas 80. That is a large crate — 122 cm long on the outside — and it is worth checking against the aircraft before booking, because several narrow-body types cannot take it.

Can two animals travel in one crate?

Sometimes, and the conditions are narrow. IATA allows two compatible animals of similar size in one container only up to a stated weight and only if they are used to each other, with a larger container than either would need alone; puppies and kittens have their own age and litter conditions. Many carriers simply refuse it. The tool sizes one animal, because that is the case the formula is written for.

Is a soft carrier ever acceptable in the hold?

No. Soft-sided carriers are for the cabin only, where the constraint is the space under the seat in front and each airline publishes its own maximum. For the hold the container has to be rigid, which is what makes the interior-dimension test meaningful — a soft bag has no fixed interior. If your animal is small enough for the cabin, measure the airline's under-seat allowance rather than running this formula.

The IATA Crate Formula an Airline Measures at Check-In

Published 9/3/2026 · 6 min read · Everyday calculators

Marco Bianchi — Home, DIY & motoring writer at Allin

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In short

The IATA Live Animals Regulations size a crate from four measurements of the animal, not from its weight. A is nose to the base of the tail, B is ground to elbow, C is the width across the shoulders and D is the standing height to the top of the head or the ear tips, whichever is higher. The minimum interior is then length A + B/2, width 2C and height D. A beagle at A = 61 cm, B = 25, C = 20, D = 46 needs an interior of 73.5 × 40 × 46 cm, which is a US series 300 or a Ferplast Atlas 50. The width rule is what surprises people: it is twice the shoulder width, so it grows faster than any weight-based sizing chart suggests.

Length A + half B, width twice C, height D. The width rule is the one that fails people: a dog with 28 cm shoulders needs 56 cm of interior width, and no crate sold by weight rating tells you that.

Why the width rule catches people out

Length and height are close to the animal's own dimensions: A + B/2 is a little more than the body, and D is exactly the standing height. Width is not. The rule is twice the shoulder width, because the animal must be able to turn around inside without contorting, and turning needs room on both sides at once. A dog measuring 20 cm across the shoulders needs 40 cm of interior width; at 28 cm it needs 56.

This is why weight-based sizing charts fail. Two dogs of identical mass can differ by ten centimetres across the shoulders — a whippet and a bulldog are the standard illustration — and the crate that fits one will be refused for the other at the desk. The four measurements take three minutes with a tape and remove the entire class of problem; a weight in a table does not.

Interior and exterior are two different numbers

A crate sold as a 36-inch model has an exterior length of 36 inches and an interior of 32.5 — nearly nine centimetres of wall, door frame and ventilation moulding. The IATA test applies to the interior, because that is the space the animal has; the airline's hold-door and pallet limits apply to the exterior. Both numbers matter and only one is printed on the shelf label, which is why the table above carries both.

It also explains a gap in the European data. Ferplast publishes exterior dimensions for its Atlas range and no interior figures at all, so the IATA test in the tool runs against the American interior column and the Atlas equivalence is matched on exterior length — an approximation by construction, and stated as one. The two ranges interleave rather than nest: a US 200 at 71 cm sits between Atlas 30 at 60 and Atlas 40 at 68, and the nearest is not always the next one up.

The crate is necessary and not sufficient

Sizing is one requirement among several, and the others are not computable. The crate must be rigid plastic or wood with a metal door, ventilated on at least three sides for international carriage, closed with bolts rather than the plastic clips many crates ship with, and fitted with spacer bars so the ventilation cannot be blocked by adjacent freight. Wheels have to be removed or immobilised. Most airline refusals at the desk are about these, not about the dimensions.

And the airline's own rules sit on top of IATA's. Carriers set their own maximum crate dimensions by aircraft type, refuse certain breeds outright, close bookings in hot months and cap the number of animals per flight. The calculation gives you a floor for the crate size; the carrier gives you the ceiling and the conditions, and the only safe order is to ask them first and buy second.

Exterior length

The two numbering systems, matched on exterior length
US series	Interior (in)	Exterior length	Nearest Atlas
100	18.75 × 13.5 × 14.5	53 cm	Atlas 20 — 58 cm
200	24.25 × 18.25 × 19.5	71 cm	Atlas 40 — 68 cm
300	29.5 × 19.75 × 23.5	81 cm	Atlas 50 — 81 cm
400	32.5 × 22 × 26	91 cm	Atlas 60 — 91 cm
500	36.25 × 24.75 × 28.8	102 cm	Atlas 70 — 101 cm
700	44 × 29 × 32.5	122 cm	Atlas 80 — 118 cm

Frequently asked questions

What crate size does a labrador need?: Measure yours, but as an order of magnitude: A = 90 cm, B = 38, C = 28, D = 62 gives a required interior of 109 × 56 × 62 cm, which is a US series 700 or a Ferplast Atlas 80. That is a large crate — 122 cm long on the outside — and it is worth checking against the aircraft before booking, because several narrow-body types cannot take it.
Can two animals travel in one crate?: Sometimes, and the conditions are narrow. IATA allows two compatible animals of similar size in one container only up to a stated weight and only if they are used to each other, with a larger container than either would need alone; puppies and kittens have their own age and litter conditions. Many carriers simply refuse it. The tool sizes one animal, because that is the case the formula is written for.
Is a soft carrier ever acceptable in the hold?: No. Soft-sided carriers are for the cabin only, where the constraint is the space under the seat in front and each airline publishes its own maximum. For the hold the container has to be rigid, which is what makes the interior-dimension test meaningful — a soft bag has no fixed interior. If your animal is small enough for the cabin, measure the airline's under-seat allowance rather than running this formula.

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