How to Choose a Dog Backpack for Hiking | Fit and Load Rules

Buying a dog backpack by the “medium” or “large” label is the fastest way to end up with a pack that sways, rubs, or restricts your dog’s front legs. The right way to choose a dog backpack for hiking starts with one measurement: chest girth at the widest point just behind the front legs. Compare that number to the manufacturer’s size chart, and every other decision—capacity, strap placement, fabric—gets easier.

Start With A Girth Measurement, Not A Size Label

Every reputable pack maker sizes by chest measurement. Ruffwear’s official guidance asks for the dog’s girth at the widest part of the ribcage, and their packs are sized off that number. The Kurgo Baxter also uses chest measurements, coming in at 3.75 liters, while the Ruffwear Approach follows the same sizing logic.

Measure snugly but not tight—you want the tape level and flat. Record the number in inches, then check it against the size chart for the specific pack you want. A dog that measures 26 inches around the chest may sit at the top of one brand’s medium and the bottom of another’s large.

Beyond girth, check two things while the pack is on but empty:

• Armpit clearance: the pack must not contact the elbows or restrict full front-leg extension.
• Rib-cage placement: side straps should sit on the ribs and never extend past the last rib.

Match Capacity To Trip Length And Dog Condition

Small packs in the 3–8 liter range—like the Outward Hound DayPak—are best for short day hikes and urban walks. Larger saddlebag-style packs, such as the 19-liter Ruffwear Palisades, suit longer trips where the dog carries more gear. The AlphaPak Adventurer offers removable saddlebags for flexibility between the two.

Load weight matters more than pack volume. Most sources set the ceiling at 25% of body weight, but that top number is only for extremely well-conditioned, experienced dogs. Ruffwear’s own guidance says to start under 25% and choose by the dog’s activity level and the gear volume you need. Wilderdog’s official product guidance is stricter: dogs should initially carry no more than 10% of body weight, including the pack itself.

For a first hike, plan on 5–10% of body weight and increase gradually only if your dog shows no sign of fatigue or gait change.

Adjust Straps, Balance The Load, And Watch For Trouble

Put the pack on empty first. Adjust the chest, belly, and shoulder straps so the pack sits snugly but not tightly—one common guide recommends a two-finger fit under the straps. Load both sides equally, placing heavier items closest to the dog’s body, and test the fit on a short leash walk before you hit the trail.

During the hike, remove the pack at rest stops and recheck it after scrambles, jumps, or water crossings. Watch for short-striding, stumbling, head lowering, excessive panting, or redness and hot spots where the pack contacts the skin. Any of these means the fit is wrong or the load is too heavy.

Choose Fabrics, Padding, And The Right Pack Style

Prefer durable, water-resistant ripstop nylon with padded contact points that reduce rubbing. Look for multiple adjustment points—chest, belly, and shoulder—so you can fine-tune the fit and cut down on shifting. The Mountainsmith K9 uses perforated mesh specifically to improve hot-weather breathability.

Carrier-style backpacks follow different rules than saddlebag packs. Carriers focus on weight limits, interior dimensions, ventilation, padding, and secure closures, and they suit small dogs, seniors, and brachycephalic breeds that need to be carried for stretches. Saddlebag packs focus on girth fit, strap placement, and load balance, and they work best for healthy adult dogs.

When you’re ready to compare specific models side by side, our tested roundup of the best dog backpacks breaks down the top options by fit, capacity, and value. Ruffwear’s guide to choosing the right dog pack offers the same sizing logic directly from the manufacturer.

The most common mistakes are buying by label instead of measurement, treating the 25% ceiling as a target rather than a limit, and skipping the gradual conditioning phase. A pack that fits well and carries a sensible load turns your dog into a helpful hiking partner instead of a sore one.