Getting the right backpack size starts with a few quick measurements and an honest look at how your dog likes to sit and settle. A well-fitted dog backpack should feel snug and secure without squeezing—especially around the chest and shoulders—so your pup stays comfortable and supported on walks or travel days.
Use a soft measuring tape (or a string and ruler), a notepad, and a few treats to help your dog stand calmly.
Wrap the tape around the widest part of your dog’s ribcage, usually just behind the front legs. This is typically the most important measurement for backpack fit because straps and harness-style supports rely on the chest for stability.
Measure from the base of the neck (where a collar naturally sits) to the base of the tail. This helps ensure the backpack body doesn’t ride too long or bunch up as your dog moves.
Measure around the base of the neck. Some backpack styles have structured openings or adjustable neck areas, and this measurement helps prevent rubbing.
Even with perfect measurements, a backpack has a maximum weight rating. Check your dog’s current weight and choose a carrier that’s designed to support it for safety and durability.
Match your dog’s chest measurement to the brand’s size chart first, then confirm back length and weight limits. If your dog falls between sizes, sizing up is often more comfortable—especially for fluffy coats, broad chests, or dogs who prefer extra room to curl.
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There isn’t one exact number—chest size varies by breed and build. Many dogs around 38 pounds commonly measure somewhere in the mid-20s to low-30s inches in chest girth, but measuring is the only reliable way to confirm.
“20 inches” often refers to height at the shoulder, not chest or back length. For backpacks and carriers, chest girth and weight matter most, so measure those in addition to height.
Use chest girth as the primary measurement, then check neck and back length against the clothing size chart. If your dog is between sizes, choose the size that fits the chest and adjust for length if possible.
