What this calculator does
A crate has to let a dog stand up, turn around and lie down stretched out. That sets two measurements: length from nose to base of tail plus a buffer, and height at the shoulder or sitting height plus a buffer. Everything else about crate choice is preference.
Bigger is not automatically better. A crate sized well beyond the dog gives it room to use one end as a toilet, which works directly against house training. For a growing puppy the usual approach is a crate sized for the adult dog with a divider moved along as it grows, rather than buying two.
The formula
The buffer is added to the dog measured length to give the minimum crate length, and to its sitting height to give the minimum height. The buffer is chosen by size band, from 5 cm for a small dog to 10 cm for a large one, which keeps the proportion sensible across the range. The result is given in centimetres and in inches, since crates are sold in both.
| Term | Meaning |
|---|---|
| Nose to tail base | Measured with the dog standing, from the tip of the nose to where the tail joins the body. The tail itself is not included. |
| Sitting height | From the floor to the top of the head with the dog sitting, which is taller than standing shoulder height. |
| Buffer | Extra space so the dog can turn and stretch, from 5 to 10 cm depending on size. |
The inputs explained
| Field | What to enter |
|---|---|
| Nose-to-tail length (standing) (cm) | Nose to base of tail, in centimetres, measured with the dog standing. |
| Floor-to-head height (sitting) (cm) | Sitting height in centimetres, floor to the top of the head. Use sitting rather than standing height, since it is the greater of the two. |
| Dog size | The buffer for the dog size band. |
When to use it
Buying a crate for the first time
Crate sizes are sold by number and by breed guess, neither of which tells you whether a particular dog fits. Two measurements settle it.
Sizing for a puppy
Measure the expected adult dimensions and buy for those, using a divider to keep the usable space small while house training.
Checking a travel crate
Airline crate rules are stricter than home use and generally require the dog to stand fully upright with clearance above the head, so add more than the buffers here for flying.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
What crate length does each dog size need?
A range of dog lengths with the sitting height and buffer held fixed.
| Nose to tail base | Minimum crate length | Minimum crate height | In inches |
|---|---|---|---|
| 40 cm | 48 cm | 63 cm | 19″ long × 25″ high |
| 55 cm | 63 cm | 63 cm | 25″ long × 25″ high |
| 70 cm | 78 cm | 63 cm | 31″ long × 25″ high |
| 90 cm | 98 cm | 63 cm | 39″ long × 25″ high |
Questions
Can a crate be too big?
Yes, for house training. A dog that has room to move away from its bed can use the far end as a toilet, which undermines the main behavioural reason for crating. For a settled adult dog that is already reliably house trained, extra space does no harm.
Should I measure standing or sitting height?
Sitting, because it is taller. A dog that can sit up without hitting its head can certainly stand comfortably. Measuring standing shoulder height instead will undersize the crate.
What size crate does a puppy need?
One sized for the adult dog, with a divider fitted. Buying small and replacing it is more expensive, and buying large without a divider makes house training harder. Most crates sold for larger breeds include a divider panel for this reason.
Do airline crates use the same sizing?
No, they are stricter. Airlines generally require the dog to stand fully upright with clearance above its head, turn around and lie down naturally, and they specify ventilation and construction as well. Check the specific airline requirements rather than relying on a home crate size.
For a rabbit enclosure rather than a dog crate, see the rabbit cage size calculator. For harness fitting, see the dog harness size calculator.