A crate is the one thing where buying big is a mistake: a dog will not soil where it sleeps, and a crate with a spare corner has somewhere that is not the bed. Enter your dog's length and height, or pick a breed, for the smallest crate that still lets them stand and turn.
The one place where buying big is the mistake
Almost every sizing decision rewards a little extra room. This one punishes it, and that is why the page exists.
Crate training works on a single fact about dogs: they will not soil where they sleep. A crate sized to sleep in has no corner that is not the bed, so the dog holds on, and the habit forms. Give the same dog a crate with a spare corner and you have handed them a bathroom at the far end. The crate still looks kind. It has simply stopped doing the job you bought it for.
Room to stand up, turn around and lie down flat is the requirement. Room to pace is not.
Two measurements, and either can decide
crate length = dog length (nose to base of tail) + 4 in
crate height = dog height (floor to top of head, sitting) + 2 in
buy the smallest crate that clears BOTH
The two allowances differ on purpose. Four inches of length lets a dog turn around; two of height is enough because published crate heights are already drawn around a sitting dog, and adding four double-counts room that is built in. Length is the one people check. Height is the one that catches them out, because a tall narrow dog can fit inside a smaller crate's footprint and still not be able to sit up in it. This page tells you which of the two drove your answer, so you know whether you have room to spare or none at all.
Worked example
A Labrador at 30 in long and 23 in tall needs 34 in of length and 25 in of height, which makes it a 36 in crate, and both dimensions drove it: the 30 in crate is too short and too low at once. Now take a Dachshund: 20 in long on 9 in of leg. That needs 24 in of length and 11 in of height, so it is a 24 in crate and height never enters the conversation. A dog the same length built tall would need a bigger crate for the headroom alone, on identical length. Two dogs, same body length, different crates.
A puppy is the exception, and it inverts the other two dog pages
On a collar and a harness, buying the adult size for a puppy is the mistake: a collar they can back out of, a harness they can reverse out of. Here it is the correct answer, and the reason is a piece of hardware rather than a principle.
Crates ship with a divider panel. Buy the adult crate, panel it down to the space the puppy needs today, and move the panel out as they grow. You get one crate instead of three, and the house training keeps working the whole way through because the usable space stays right at every stage. An adult crate with no divider fitted is the worst of both: too much money and a bathroom at one end.
How to measure, and what not to include
Length runs from the nose to the base of the tail, not to the tip. No dog needs crate space for its tail, and measuring to the tip is how people end up a size larger than they need, which on this page is the wrong direction to err.
Height runs from the floor to the top of the head with the dog sitting rather than standing. Sitting is the tallest a dog gets inside a crate, and it is the position they will spend the most time in when something interesting happens outside.
Check internal against external
Crate sizes are far more consistent between makers than collar or harness letters, which is the one thing that makes this the easiest of the three to buy. An 18, 24, 30, 36, 42 or 48 means roughly the same thing everywhere.
The catch is that listings quote external dimensions about as often as internal ones, and the difference is real once you account for the frame and the tray. The numbers on this page are internal, because internal is the space the dog actually gets. If a listing does not say which it is quoting, assume external and check.
Frequently asked questions
What size crate does my dog need?
The smallest one that clears both their length and their height with about four inches to spare on each. Length is nose to the base of the tail, height is floor to the top of the head with the dog sitting. Either measurement can decide the size, so check both: a tall narrow dog can fit the length of a smaller crate and still need the taller one.
Is a bigger dog crate better?
No, and this is the most common crate mistake. Crate training works because a dog will not soil where it sleeps, but a crate with a spare corner has somewhere that is not the bed. Oversize it and you remove the mechanism that makes it work. Room to stand, turn around and lie down flat is the requirement; room to pace is not.
What size crate for a puppy?
Buy the adult size and use the divider. This is the opposite of the advice for a collar or a harness, where buying for the adult is dangerous, and it works because crates ship with a divider panel. Fit the adult crate, panel it down to the space the puppy needs now, and move the panel out as they grow. One crate, and house training still works at every stage.
How do I measure my dog for a crate?
Two straight lines. Length from the nose to the base of the tail, not the tip, since no dog needs crate space for its tail. Height from the floor to the top of the head with the dog sitting, because sitting is the tallest they get inside a crate. Add about four inches to each and find the smallest crate that clears both.
What size crate for a Labrador or German Shepherd?
A Labrador usually takes a 36 in crate and a German Shepherd a 42, though both sit close enough to the boundary that measuring is worth the two minutes. Adult Labradors run about 30 in long and 23 in tall; German Shepherds about 32 by 25. Individuals vary enough to cross a size line.
Are dog crate sizes standard between brands?
More standard than collar or harness letters, which is the one thing that makes this easier. Crates are sold by nominal length in inches, and an 18, 24, 30, 36, 42 or 48 means roughly the same thing everywhere. Check whether a listing quotes internal or external dimensions though, because that difference is real and it is usually external.
What size crate for a Dachshund?
A 24 in, and it is a good illustration of why height and length are separate questions. A Dachshund is long and low, about 20 in of body on 9 in of leg, so length decides the crate entirely and height never comes into it. A dog the same length but built tall would need a bigger crate for the headroom alone.
Should I get a crate my dog can grow into?
Yes, but only with a divider fitted. An adult-sized crate with no divider gives a puppy a bathroom at one end, which undoes the house training the crate is meant to support. With the divider in and moved out gradually, the adult crate is the right purchase from day one and the only one you will need.