Size Selection for K4 Pack Systems

There is no such thing as a one-size-fits-all pack system. To achieve optimal comfort and performance, you need a pack system that fits your unique body shape and size.

This article will explain how to select the correct K4 Frame size options you need to choose from when ordering a K4 Pack System.

The K4 Frame also features micro-adjustments that you can make to fine-tune the frame’s fit when you receive the pack. Please refer to the K4 Fitting & Adjustment page if you are looking for information on adjusting your K4 Pack for optimal fit and performance. If you are looking for sizing or fitting information for our previous K3 Pack Systems, go to K3 Fitting & Adjustment.



First, we need a physical measurement around the crest (highest point) of your hip's bone structure. This physical point of your anatomy is called your Iliac Crest. To find the Iliac Crest, put your finger about 1" below your navel, then feel out toward your side. Find the high point of the hip bone, which is your Iliac Crest.

How to Find & Measure your Iliac Crest

Using your Iliac Crest measurement, select your hipbelt size from the chart below.

K4 Hipbelt Size Chart


  • DO NOT USE YOUR PANT’S SIZE as a substitute for an iliac crest measurement when determining your K4 Hipbelt size on the chart above.
  • DO NOT “ROUND UP” your Iliac Crest measurement at all. Our size guidelines account for having plenty of room for clothing layers and other factors. In the photos above, Mark measures 33.75” and since he measures slightly under 34”, he should select a SM hipbelt (30-34”) and should not size up to a MD hipbelt (34-38”).


Beginning with your height, look at the chart below. In many instances, you will find 2 frame height options listed for your height. Because all of our frames have 6” of torso adjustment on the frame, both frame height options listed for your height will fit you. It isn’t that one of the listed frame heights “will fit” and the other “won’t fit” — instead, either frame height option can fit you, but each will offer slightly different benefits for your build, or for your intended application.

K4 Frame Height Chart

How to choose between two frame height options...

As clarified above, either of the two frame height options listed for your height will fit you. Choosing between the two becomes a matter of preference or nuance for your body shape and/or intended use…

Consider the SHORTER option if...

  • BODY SHAPE — You are pretty average, and/or are lean and athletic in your overall physique. You are not overly “big and broad” through the upper body, and/or…
  • LEGS & TORSO — You have longer legs (and therefore a shorter torso) than average for your height, and/or
  • HUNTING AREA — You hunt a lot of thick cover and want to prioritize mobility and head-clearance for ducking under cover, and/or..
  • HUNTING STYLE — You mostly day hunt (from the truck, trailhead, or a backcountry basecamp) and do not commonly carry multiple days worth of food and gear on your back while hunting.

Consider the TALLER option if...

  • BODY SHAPE — You are big and “barrel chested” in your upper body, or are really “thick” (more than just moderately overweight) throughout the midsection and upper body, and/or…
  • LEGS & TORSO — You have shorter legs (and therefore a longer torso) than average for your height, and/or…
  • HUNTING AREA — You hunt more open country and want to prioritize every bit of load-hauling performance, even if that comes at a slight reduction of head clearance from the additional frame height, and/or…
  • HUNTING STYLE — You commonly backpack hunt, carrying multiple days worth of food and gear (35lbs+) on your back while hunting.


  • EITHER OPTION WILL FIT YOU if there are two frame height options listed for your height. Choosing between the two is only a matter of preference and priority, based on the criteria mentioned above.
  • THE PERCENTAGE LISTED FOR EACH OPTION is there as a guide. For example, 80% of guys who are 5’ 10” tall would be best in the 25” frame height. The other 20% of guys may choose the 26.5” frame — either because they are very big and broad-chested in their build — or, for example, they are prioritizing heavy load performance because they will be carrying a 60lb pack for the entire duration of a 10-Day sheep hunt in Alaska.
  • YOU CAN CHANGE AND CUSTOMIZE THE FRAME HEIGHT. We do sell the carbon fiber frame stays by themselves, so if you want to own both 25” and 26.5” stays and swap them out as needed, you certainly can do that. You can also cut down frame stays to customize your frame height to a specific size that you prefer. If you want a 25.5” frame, for example, you can trim an inch off of the 26.5” frame stays.
  • THE BEST OPTION FOR WOMEN is generally our EXS System. For more information about frame height selection for women, and the other unique benefits of the K4 EXS Pack System, check out