Colin FosterBy Colin Foster

Updated November 2026

A hiking backpack size chart works only when you know two numbers: your torso length and the volume you need for your trips. This guide shows you how to measure your torso, read a size chart against it, and choose a pack capacity that matches how long you actually spend on the trail. By the end, you will know which size to order before you spend money on a pack you cannot return.

Step 1: Measure Your Torso Length

Torso length is the single most important number on any hiking backpack size chart. Most packs are sized by this measurement, not by your height. The frame, shoulder straps and hip belt all sit at fixed points along your spine, so a pack that is too long or too short will never carry well.

Shopping for one? See our guide: 4 Best Hiking Backpack Women's (2026): Expert Picks.

  1. Have someone help you, or use a soft tape measure and a friend.
  2. Stand upright and tilt your head forward so the bony bump at the base of your neck (C7 vertebra) stands out.
  3. Measure from that bump straight down to the top of your hip bones (the iliac crest), following your spine.
  4. Record the number in inches. Most charts list sizes such as S, M and L by torso range, often around 15 to 17 inches for small, 17 to 19 for medium and 19 to 21 for large, though exact ranges vary by brand.

Step 2: Match Your Torso to the Chart Size

Once you have your number, find the matching torso range on the size chart. If you fall between two sizes, check the hip belt next. Manufacturers usually size hip belts by waist circumference, and the belt should wrap your hip bones, not your waist.

Torso length (approx.) Typical size label What to check
Under 17 in XS or S Shoulder straps should not sit on your neck
17 to 19 in M Hip belt sits on hip bones with the load lifter at about 45 degrees
19 to 21 in L Frame top stays below the shoulder blades
Over 21 in XL or adjustable Adjustable suspension may fit a wider range

Ranges above are general. Always confirm against the specific brand’s chart, because the same label can mean slightly different measurements from one manufacturer to another.

Step 3: Choose Pack Volume for Your Trip Length

Size charts also list capacity in liters. Capacity should follow trip length and how much gear you carry, not your body size. A rough guide many hikers use:

  • Day hikes (under 8 hours, no overnight gear): 15 to 25 liters
  • Overnight (1 to 2 nights): 35 to 45 liters
  • Three to five nights: 50 to 65 liters
  • Longer trips or winter gear: 65 liters and up

If you often switch between day hikes and overnights, a pack with a compression system lets one bag handle both. For guidance on choosing a specific volume, see 30 L Hiking Backpack: How to Choose the Right Size for Your Trips.

Step 4: Check Fit Before You Commit

Even a correct chart reading can lead to a poor fit, so test the pack with weight. Load it to roughly the weight you expect to carry, then check three things: the hip belt carries most of the load, the shoulder straps are snug without pulling on your neck, and the frame stays put when you bend and step.

Brands with trail-focused lines often publish detailed fit guides. The Mystery Ranch Hiking Backpack Guide: Sizing, Fit and Packing Tips walks through a similar process if you want more depth on adjustments.

Common Mistakes

  • Sizing by height instead of torso length.
  • Buying a large pack for short trips, which encourages overpacking.
  • Ignoring the hip belt size and buying by shoulder fit alone.
  • Trying on a pack empty, which hides how it will load.
  • Assuming a women’s pack is the same as a smaller unisex size, since frame shape and hip belt design differ.
  • A soft tape measure makes the torso measurement quick and repeatable. View on Amazon
  • Adjustable hiking pack with a fitting system lets you fine-tune torso length after purchase. View on Amazon
  • Pack liner bags keep gear dry and help you test loads before a trip. View on Amazon

FAQ

How do I measure torso length for a hiking backpack?

Measure from the bony bump at the base of your neck down to the top of your hip bones, following your spine. Use that number to find your size on the brand’s chart.

Should I size a hiking backpack by height?

No. Height is a weak predictor of fit, because pack frames and hip belts are sized to torso length and waist, not overall height.

What liter size is best for a first backpacking trip?

For one or two nights, many hikers find a pack in the 35 to 45 liter range works well, though exact needs depend on your gear and season.

Conclusion

A hiking backpack size chart is only useful when paired with an accurate torso measurement and a realistic volume for your trips. Measure first, match the chart, then load-test the pack before you head out. Taking these steps keeps the weight on your hips and your shoulders comfortable for the full day.

Ready to choose one?

Colin Foster

About Colin Foster

Colin Foster is part of our editorial team and reviews and edits our backpacks & packing systems guides, checking product details against manufacturer specifications and owner feedback.