Should I measure my pet standing or lying down?

For most carriers, measure your pet standing in a natural position. For soft-sided carriers that allow some compression, you can also measure them lying down to ensure they can stretch out. Always refer to the carrier's specific measurement guidelines.

What if my pet is between sizes?

Choose the larger size if your pet is close to the upper limit. A slightly roomier carrier is safer and more comfortable. However, for airline travel, ensure the carrier still fits within the airline's size restrictions.

How do I measure a cat that won't stay still?

Use a treat or toy to keep them standing. Alternatively, measure them while they are asleep or relaxed. You can also gently hold them in a standing position with help from another person.

Can I use a soft-sided carrier for airline travel?

Yes, soft-sided carriers are often preferred because they can flex slightly to fit under the seat. However, ensure the carrier meets the airline's exact dimensions and that your pet can stand and turn around inside.

How do I measure a pet with a thick coat?

Measure your pet's body, not the fur. Press the tape gently against the body to get an accurate measurement. If the coat is very thick, consider trimming or using a larger carrier to account for bulk.

Pet Carrier Size Guide: How to Measure Your Dog or Cat

Published July 19, 2026 · Reviewed by the Unbiased Advice & Insights editorial team · How we research and score

Choosing the right pet carrier starts with accurate measurements. Our editorial team compared specifications, buyer feedback and key decision factors to bring you this guide. Follow these steps to ensure a comfortable and safe fit for your dog or cat.

Why Measuring Matters

A carrier that is too small can cause stress, discomfort, and even health issues for your pet. For example, a cramped carrier may lead to anxiety, muscle stiffness, or overheating. A carrier that is too large may not provide enough security and can be unsafe in vehicles or on airplanes, as your pet could slide around during sudden stops. Proper measurements help you find a carrier where your pet can stand, turn around, and lie down comfortably. For airline travel, strict size limits apply, so measuring correctly can save you from last-minute hassles at the gate. Additionally, a well-fitted carrier reduces the risk of escape and makes carrying easier for you.

Step-by-Step Measuring Instructions

You will need a flexible measuring tape (like a sewing tape) and a flat surface. Have your pet stand on all four feet in a natural position. If your pet is wiggly, have a helper gently steady them. For cats, you may need to measure while they are distracted with a treat.

Measure length. Place the tape at the base of the tail (where it meets the body) and extend it to the tip of the nose. Do not include the tail length. Record this number. For long-bodied breeds like Dachshunds, ensure the tape follows the curve of the spine.
Measure height. Starting from the floor, measure up to the top of the shoulder (the withers). For dogs, this is the highest point of the back. For cats, measure to the top of the head if they hold it upright. Record this number. For breeds with erect ears, measure to the ear tips if the carrier has a low ceiling.
Measure width. While your pet is standing, measure the widest part of their body, usually across the chest or hips. This helps ensure they can turn around inside the carrier. For deep-chested breeds like Bulldogs, this measurement is critical.
Check weight. Weigh your pet on a scale. Carrier weight limits are as important as dimensions. Overweight pets may exceed the carrier's capacity, leading to discomfort or safety issues.

Add 2 to 4 inches to the length and height measurements to allow for movement and comfort. For airline carriers, check the specific airline's maximum dimensions and do not exceed them. If your pet is between sizes, opt for the larger size, but verify it still fits under the seat if flying.

Airline Restrictions and Tips

Each airline has its own size requirements for in-cabin pet carriers. Most require the carrier to fit under the seat in front of you. Common maximum dimensions are around 18 x 11 x 11 inches (length x width x height) but vary by airline. For example, Delta allows 18 x 11 x 11 inches, while American Airlines allows 19 x 13 x 9 inches. Always check your airline's website before purchasing. Soft-sided carriers are often preferred because they can flex slightly to fit. Remember that your pet must be able to stand and turn around inside the carrier even when it is under the seat. Some airlines also have weight limits for the pet plus carrier (often 20 pounds total). Additionally, some airlines require documentation of your pet's measurements at check-in, so keep a record. For international flights, restrictions may be stricter, and carriers may need to meet IATA standards.

Breed-Specific Considerations

Different breeds have different body shapes. For example, long-bodied breeds like Dachshunds need extra length, while deep-chested breeds like Bulldogs need more width. Brachycephalic breeds (flat-faced dogs like Pugs, French Bulldogs, and Persian cats) are more prone to breathing issues and require carriers with ample ventilation and airflow. For these breeds, avoid carriers that restrict the face area and choose ones with mesh panels on multiple sides. For large breeds like Golden Retrievers, you may need a wheeled carrier or a carrier designed for cargo travel. Always measure your individual pet rather than relying on breed averages, as individual sizes vary. For example, a small Labrador may fit in a large in-cabin carrier, while a large one will not. Also consider your pet's age: puppies and kittens grow quickly, so you may need to size up soon.

Common Mistakes to Avoid

One common mistake is measuring your pet while they are lying down, which gives inaccurate height and length. Always measure while standing. Another mistake is forgetting to account for your pet's ears or tail if the carrier has a low ceiling. For cats, their ears may stick up, so measure to the top of the head or ear tips. Also, do not rely solely on weight; two pets of the same weight can have very different dimensions. Finally, avoid buying a carrier based on breed labels alone, as sizes vary within breeds. Always measure your specific pet and compare to the carrier's interior dimensions.

By taking accurate measurements and considering airline and breed factors, you can confidently choose a carrier that keeps your pet safe and comfortable. Check the current price on Amazon for a variety of carriers that meet your pet's specific needs.

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See our full buying guides hub and our research and scoring methodology. We compared specifications and verified owner feedback; we did not physically test every product.