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Please note, breeds shown in this guide are for example purposes only. Given that breeds can vary drastically in length/girth and aren't confined to certain sizes the most successful way of choosing a size is to base it on measurements, not breed. 

How to Measure for a K9 Sport Sack Dog Carrier Backpack?
You will need two measurements, girth (around the widest part of your dog's chest) and length (from the start of their collar to the base of their tail) as displayed in the diagram below. 

If you find your dog is between sizes and still growing (perhaps you would like to opt for a bigger size backpack to last) or your dog's breed is short legged/long bodied then we can help. Alternatively if your dog is fully grown and right on the cusp of two sizes we can help too.

For the scenarios above, in most cases it is best to go up one size (or two for puppies) since the girth is adjustable and extra length can be fixed with the use of booster blocks that add a 3" lift to the backpacks. Another option is to use blankets/towels/cushions since these can instead be used in the bottom of the bag. It's best for a bag to be a little too big than too tight/short, especially with growing pups! 

You can contact us at or on our live chat between 8am-8pm if you need any help with sizing or choosing a version as we're always happy to help!

Please continue down the page for individual product guides and recommendations.

K9 Sport Sack Size Guide


Air 2 Sizes

K9 sport sack air 2 size guide

Plus 2 Sizes
K9 sport sack plus 2 size guide

Rover 2 Sizes
K9 sport sack rover 2 size guide

Snuggler Sizes

Length - Measure from dogs collar to the base of their tail.
Girth - Measure the widest part of your dog's chest. 

 Length Girth Size Recommendation
10 - 17" / 23 - 43 cm Up to 27" / 69 cm XS/S Measure their size
17-23" / 43-58 cm Up to 31" / 79 cm M/L Measure their size

Designed to be used with the K9 Sport Sack Air, Plus 2 and Urban models therefore means these will fit the corresponding dog breeds and sizes supported by each backpack's sizing chart.
The XS/S snuggler will fit the XS/S Air, Plus 2 and Urban models whilst the M/L snuggler will fit the M/L Air, Plus 2 and Urban models.

Sport Sleeper Sizes

Dimensions - 20in x 20in (51cm x 51cm)
Thickness - 1.5in (3.5cm)
Weight - 6.77oz (191g)

Large/Extra Large:
Dimensions - 30in x 30in (76cm x 76cm)
Thickness - 1.5in (3.5cm)
Weight - 13.74oz (382g)

Trainer Sizes
K9 sport sack trainer size guide

Urban 2 Sizes

k9 sport sack urban 2 size guide