Measure your dog, add a practical comfort allowance, then round the crate length up to a common retail size. The calculator keeps width generous enough for turning around rather than using length alone, and it treats the standard retail size as a shopping shortlist rather than a guarantee of internal space.
Small dogs use about 2 in of allowance; medium dogs use about 3 in; large dogs use about 4 in.
Recommended width is the larger of twice shoulder width or 55% of recommended length.
The standard crate length is rounded up to the next common crate size.
Fit checklist
After choosing a likely size, check the internal dimensions from the specific manufacturer. External crate dimensions can be several inches larger than the usable internal space, and bedding, trays, sloped sides, or rounded corners can reduce the room your dog actually has.
Worked example
A medium dog measuring 28 in long, 26 in sitting height, and 9 in wide needs about 31 x 18 x 29 in internally, so a 36 in crate is the safer standard size to compare.
Common crate sizing examples
Use these as examples only. The calculator result should be based on your dog's actual length, sitting height, and shoulder width.
Dog measurement
Allowance used
What to compare
11 in long, small dog
Add about 2 in
Start around an 18-22 in crate and check width.
20 in long, medium dog
Add about 3 in
Compare 30 in crates and confirm sitting height.
22 in long, small dog
Add about 2 in
Start around a 24 in internal-length crate.
28 in long, medium dog
Add about 3 in
Compare 36 in standard crates and check internal dimensions.
34 in long, large dog
Add about 4 in
Compare 42 in crates if internal height and width also fit.
38 in long, extra-large dog
Add about 4 in
Compare 48 in crates and inspect door height.
Before you buy
Measure from nose to base of tail, not to the tail tip.
Measure sitting height to the top of the head or ears, whichever is higher.
Compare internal crate dimensions, not only the product name.
Use a divider for puppies when the adult-size crate is much larger than they need today.
Check whether bedding or a crate pad reduces usable height.
Confirm door size if the dog is tall, elderly, or reluctant to duck into a crate.
Recheck fit after growth, weight change, injury, or a change in bedding.
For travel, confirm airline, vehicle, or carrier rules separately.
When this estimate may be wrong
Airline travel crates can have different requirements from home crates.
Very broad-chested or long-backed dogs may need extra width or length.
Dogs recovering from injury or with mobility issues may need advice beyond a simple size estimate.
Retail crate names often use outside length, not internal usable length.
Breed examples are only starting points; individual dogs vary within a breed.
A crate that fits at home may not satisfy airline or transport rules.
FAQ
Should I size up for a puppy?
Usually yes if you are buying one crate for adult size, but use a divider so the puppy's current sleeping area is not too large. Remeasure regularly and move the divider as the puppy grows.
How much extra space should a crate have?
The dog should be able to stand, turn around, and lie down comfortably. The calculator adds a practical comfort allowance, but the final check should use the crate's internal dimensions and the dog's movement inside the crate.
Should I use internal or external crate dimensions?
Use internal dimensions for dog fit. External dimensions are useful for checking whether the crate fits in your room or vehicle, but they can overstate the space available to the dog.
Why does the calculator ask for sitting height?
Sitting height catches cases where a dog can stand but cannot sit naturally without the head or ears touching the roof. Measure to the highest point of the head or ears.
Is breed enough to choose a crate?
No. Breed examples are only starting points because dogs vary within the same breed. Measure length, sitting height, and shoulder width before buying.
What if my dog is between two crate sizes?
Compare the larger size first, then check whether it creates too much unused space for your use case. For puppies, a divider is often more practical than buying a cramped crate.
Does bedding change the crate size?
It can. Thick beds and pads reduce usable height and floor space. Check the fit with the bedding you actually plan to use.
Can I use this for airline travel crates?
Use it only as a starting measurement guide. Airlines and transport providers can have specific crate rules, so confirm current requirements directly before travel.
How do I measure shoulder width?
Measure across the broadest comfortable part of the shoulders while the dog is standing naturally. Do not use collar width or harness width as a substitute.
What are signs the crate is too small?
Common signs include crouching, ears or head touching the roof, awkward turning, or inability to lie down in a normal resting position.
This is a sizing guide, not airline, travel, or veterinary advice.