Carrier sizes
Both sizes expand the same way. The only question is whether you ever plan to fly.
| Size | Closed (L x W x H) | Expanded width | Folded flat | Comfortable up to |
|---|---|---|---|---|
| Cabin Fit (Small) | 15.75" x 9.84" x 9.84" 40 x 25 x 25 cm |
25.6" / 65 cm | 2.76" / 7 cm | 13 lbs / 6 kg |
| Large | 17.72" x 11.81" x 11.81" 45 x 30 x 30 cm |
32.3" / 82 cm | 2.76" / 7 cm | 16 lbs / 7.5 kg |
Which one do I need?
Choose Cabin Fit (Small) if you ever fly. It is under the published under-seat limit of Delta, United and American in all three directions, including American's tighter Embraer limit of 17.5 x 10.5 x 10.5.
Choose Large if you are not flying. It is over the cabin limit, so it is for the car, the vet and home. More room for a bigger cat.
Airline under-seat limits
| Airline | Published limit | Cabin Fit (Small) |
|---|---|---|
| Delta | 18" x 11" x 11" | Fits, ~2" margin |
| United (soft-sided) | 18" x 11" x 11" | Fits, ~2" margin |
| American (single-aisle) | 18" x 11" x 11" | Fits, ~2" margin |
| American (Embraer jets) | 17.5" x 10.5" x 10.5" | Fits |
| Southwest | 18.5" x 13.5" x 8.5-9.5" | Tight on height (we are 9.84") |
Published limits, verified August 2026. Airlines change policies and under-seat space varies by aircraft. Bulkhead and some window seats have less room, or none. Always check your flight before you book.
Harness sizes
Measure the chest, not the weight. Two 10 lb cats can need different sizes.
| Size | Chest girth | Neck | Typical weight |
|---|---|---|---|
| M | 11" - 15" / 28 - 38 cm | 7.5" - 10" / 19 - 25 cm | 5 - 10 lbs |
| L | 15" - 19" / 38 - 48 cm | 9" - 12" / 23 - 30 cm | 10 - 20 lbs |
How to measure
- Chest: wrap a soft tape around the widest part of the ribcage, just behind the front legs. Snug, not tight - two fingers should slide under.
- Neck: at the base, where a collar would sit.
- Between sizes? Go up. A harness that is slightly loose can be tightened; one that is too small cannot be made bigger.
Long-haired cats: measure under the coat, not over it. Winter fur can add an inch that is not really there.
Not sure? Ask us first.
Email us the chest measurement and a side photo of your cat and we will tell you which size to order, before you spend anything. It takes us two minutes and saves you a return.
And if we get it wrong: do not ship it back. Tell us and we will send the right size. Wrong-size returns are our problem, not yours to pay for.