More inventory is on the way this Spring! Be sure to sign up for our out of stock alerts!
Shopping Cart


Our backpack carrier sizing is based off of one metric - the length of your dog, from its collar to the base of its tail.

If your dog is still growing, in between sizes, or if the dog owner needs a bigger carrier to fit around his/her frame, consider a K9 Booster Block to make sure your carrier fits not only the dog, but its owner properly.




The AIR 2 backpack carrier is available in sizes: XS, S, M, and L and holds dogs ranging from 4-30 lbs (2-13 kg)

The PLUS 2 backpack carrier is available in sizes: S, M, and L and holds dogs ranging from 8-40 lbs (4-18 kg)

The KNAVIGATE backpack carrier is available in sizes: XS, S, M, L, and XL and holds dogs ranging from 4-50 lbs (2-23 kg)

Buy with Confidence

Customers with an imperfect first experience report that exchanging for the correct size resolved most issues.

If your carrier is difficult to zip, seems to scrunch your pet or he/she extends too far out of the collar enclosure, try the next size up with a Booster Block and you’ll likely be surprised that your passenger will settle right into place.

If your pet is drowning in fabric, sliding down inside the bag or able to exit through a top that is too loose, exchanging for a smaller size or fine-tuning with a Booster Block is likely to do the trick.

Additionally, most pet owners who return their K9 Sport Sack eventually make a second purchase as the excitement to take their best friend on adventures weighs heavily on dog and owner alike. According to a survey conducted in 2018 the majority of all customers who ultimately kept their second K9 Sport Sack reported that their dog needed:

  • The correct size
  • Additional training/experience

Please Don't Give Up

We understand that no sizing guide is as accurate as a product in hand so we have made exchanges simple and fast. Reach out to our knowledgeable customer support team at or (385) 515-8908 for any advice, tricks, hints or ideas to take your adventure off the leash.