Ultra Circuit

(8 customer reviews)


What Size Pack Do I Need? View Size Chart.
ULA Torso Measurement Guide
ULA Hipbelt Measurement Guide
ULA Hipbelt Measurement Guide
S v J Strap Comparison


  • Standing upright, tilt your chin to your chest.
  • Locate your C7 Vertabra—the large lump at the base of your neck.
  • With flexible tape, measure down the length and natural curvature of your spine to your iliac crest/ the top of your hipbone.
  • This measurement in inches is your torso length.

TIP: If you're between 2 sizes, order the smaller size. Still not sure? Contact us.


We've found most people in these height ranges fall into these torso/pack sizes. That being said, it is always best to measure your torso using the guide above.

If you're between sizes and you are getting a FRAMED pack, we recommend you size DOWN!

If you're between sizes and you are getting a FRAMELESS pack, we recommend you size UP!

If you have questions, or your torso size doesn’t seem to make sense for your height, please contact us.


Use the following method to determine your hipbelt inches, then head to Step 4 to see the hipbelt size you need.


Pant Waist Size + 2".


CURVY HIPS: Smallest part of your waist + 5".
STRAIGHT HIPS: Smallest part of your waist + 3".


Smallest Part of waist + 2".


Find the hipbelt measurement you calculated in Step 3 on the chart. That will be your hipbelt size.

TIP: If you are on the outer edge of a size, order the larger size. [ Ex: If you are 38", you will notice 38" is the last number of the Medium Hipbelt and the first number of the Large Hipbelt. You would want to order a Large.]


The downward slope of your shoulder profile usually determines strap preference. You can assess your shoulder slope profile by looking in a mirror or having a friend look at the angle of your shoulder from the base of your neck to your shoulder point. 

If there is relatively little or no downward slope, you have what is referred to as flat or squared shoulders.

If there is a noticeable downward slope, you have what is referred to as standard or sloping shoulders.


J-straps are the traditional straight straps. They are best suited for people with flat or square shoulders, as their flat shape provides better surface contact and less rub.


S-straps contour body curves. They are best suited for people with standard or sloping shoulders, as their contoured shape better hugs your shoulder slope.

TIP: If you have a short torso but a larger upper body, you may need a slightly longer strap. If you are very large in the upper body, you might need XL shoulder straps. Contact us, and we would be happy to make these customizations so your pack is comfortable and fits well.

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Say hello to the Ultra Circuit, the same Circuit you know and love, only stronger and lighter than ever. Purposefully constructed of Ultra 400 in high abrasion areas (bottom, back panel, and pockets) and Ultra 200 in low abrasion areas (sides, front, and collar), we’ve selected a fabric matrix that maximizes durability while keeping the pack ultralight [33.8 oz!]

In our commitment to making quality, durable backpacks that last a lifetime, we’ve been hesitant to build packs out of many popular ultralight fabrics. Why Ultra? 15x stronger than steel by weight, twice as abrasion resistant as standard 420D nylon, and waterproof to 200 psi, we’ve finally found an ultralight fabric that matches our high standards. Front pocket is ULTRA StretchMesh for added abrasion resistance. Note that to maximize water-resistance of the ULTRA Circuit, these packs do not have bladder hose ports. 

We don’t think there’s a pack out there that compares to the load carrying capabilities, comfort, and durability of the Ultra Circuit. The Ultra Circuit utilizes a 1.2 oz carbon fiber and Delrin suspension hoop, a dense internal foam frame, and a single aluminum stay to give you excellent back panel support, maximum load control, weight transfer, and pack rigidity without limiting your range of movement. Front mesh pocket, dual hipbelt pockets, and Ultra 400 adjustable side pockets make it easy to stay organized whether you’re on a thru or just out for the weekend. If you have your total pack weight down to around 30 pounds and want to feel the freedom of traveling light, the Circuit is for you.

COLOR(S): Graphite Black/Silverado Grey


WEIGHT: 33.8 OZ | 958.2 GM
VOLUME: 4,200 CU IN | 68 L
MAX LOAD: 35 LBS | 16 KG

If you have your total pack weight down to around 30 pounds and want to feel the freedom of traveling light, the Ultra 24 Circuit is for you.


  • ULTRA 400 + ULTRA 200 Fabric
  • ULTRA Hipbelt Pockets w/ YKK Waterproof Zippers
  • ULTRA Side Pockets w/ Elasticized Top
  • UltraStretch™ Mesh Front Pocket
  • Internal Suspension Hoop
  • Padded Backpanel
  • NO Water Hose Port for Max Water Resistance
  • Removable & Height Adjustable Pass-through Hipbelt
  • Rolltop Closure
  • Side/Top Compression Straps
  • Trekking Pole Loops
  • Sternum Strap
  • Contoured Shoulder Straps
  • Front Shock Cord
  • ULA Logo on StretchMesh




TOTAL VOLUME: 4,200 CI | 68 L


  • Main Body: 2,400 CI | 39.3 L
  • Front Mesh Pocket: 400 CI | 6.6 L
  • Left Side Pocket: 400 CI | 6.6 L
  • Right Side Pocket: 400 CI | 6.6 L
  • Extension Collar: 500 CI | 8.19 L
  • Left Hipbelt Pocket: 100 CI | 1.6 L
  • Right Hipbelt Pocket: 100 CI | 1.9 L
ULTRA Circuit - Front View



A: ULTRA is 15x stronger than steel by weight, twice as abrasion resistant as standard 420D nylon, and waterproof to 200 psi. Ultra is the ultimate in ultralight fabric, with the strength to go the distance in the harshest environments.

ULTRA fabric lasts longer, absorbs 80% less moisture, and has better UV resistance and color retention than traditional laminated nylon.

ULTRA is the only durable, waterproof pack fabric made from 100% recycled polyester! Every yard contains over 20 plastic bottles and saves over one pound of carbon emissions compared to standard pack fabric.

Q: WHAT IS UltraStretch™ MESH?

A: UltraStretch™ Mesh is built for maximum abrasion and cut resistance. A technical fabric, UltraStretch™ Mesh is a 4-way stretch mesh woven with the highest quality fibers for performance and longevity.


A: The suspension hoop used in the Circuit is our minimal solution to transferring load between shoulder and hip. If you imagine an upside ‘U’ you get a sense of how the hoop is positioned and how it functions. The upper arch of the ‘U’ ties into the shoulder straps, while each leg of the ‘U’ ties into the hipbelt. These points of contact allow for a range of suspension flexibility while being rigid enough to support loads up to 35 lbs. In addition, because the suspension is located on the periphery of the pack body, and the back-panel is stiffened slightly with dual density foam, the result is a pack that can handle the load but does not dictate your body’s movements — but rather responds to how you move. Personally, when the loads are kept below 35 lbs, we find this pack to be the most comfortable in the ULA line-up.


A: Every bear canister on the market will fit into the Circuit vertically and some smaller bear canisters will horizontally. Keep in mind it is best to pack something between the hard sided canister and the bottom of the pack.

To see a chart showing what bear cans fit in what ULA packs (and how),  visit our blog post “Bears! Everything You Need to Know About Backpacking in Bear Country.


A: If you are using an inflatable pad, we recommended storing it in the interior of the pack to avoid punctures. A foam pad can easily be secured beneath the top compression strap that goes over the top of the pack or beneath the front shock cord compression. Although not necessary for optimum performance, positioning your sleeping pad into the interior of the Circuit (against the back-panel) is also a good solution.

Alternately, you can build your own pack and add Bottom Straps, or a top Y-strap to carry your pad externally.


A: Each side pocket can accommodate two 1-Liter ‘Big Slam’ style bottles. A Nalgene-style bottle will also fit, but in your quest to lighten up, that should have been replaced a long time ago! In general most people can reach back and retrieve a bottle, drink, and return the bottle to the pocket without removing the pack. The top of the side pockets are angled for easier access.


A: The top of the pack closes like a dry bag (also known as a rolltop) very similar to what river runners use to create a water resistant seal for their gear bags. The back of the collar is slightly taller than the front. Once you are packed, the collar can be rolled down upon itself to effectively create a barrier to water penetration. Once rolled, each side of the collar can be buckled to the sides of the pack or the two yellow buckles on the top can also be fastened to each other.

As for access, once the collar is rolled and fastened shut, you would need to unbuckle the compression straps and unroll the collar to access the inside of the pack. However, the roll-top only needs to be rolled shut when the weather dictates. If the sky is dry, the collar can simply be folded forward. Vertical compression can still be achieved by buckling the collar to the sides of the pack.


ULTRA™ represents a new paradigm in durability and weight. Constructed with an optimal blend of UHMWPE (Ultra-high-molecular-weight polyethylene) & high-tenacity polyester, the tight weave is laminated with an eco-friendly adhesive to Challenge RUV™ film. The result is an incredibly strong, lightweight, and waterproof to 200 psi textile.

ULTRA™ is the ultimate in ultralight pack fabric, with the strength to go the distance in the most demanding environments.

ULTRA™ 200
200D Ultra PE is woven and laminated to recycled, waterproof RUV™ film. At just 3.5oz/yd2, it exceeds the technical properties of any similar weight fabric available on Earth. Tear Strength: Warp: 103.1 lb / Fill 133.2 lb. Abrasion Resistance: 4,400 cycles.

ULTRA™ 400
A high modulus pack fabric, ULTRA 400, is constructed of a 400d Ultra PE (similar to Dyneema®) with 0.5 mil RUV™ film backing. It is 20% lighter and four times as abrasion-resistant than other 400d U-PE fabrics. Weight: 4.65 oz/yd², 158 gsm. Tear Strength: Warp: 187.7 lb, Fill 161.1 lb. Abrasion Resistance: 8,800 cycles.


8 reviews for Ultra Circuit

  1. Jake Hildebrandt (verified owner)

    Consider this review a perspective on upper-limits, here me out… Just off a 100-mile CDT section through the San Juans of Colorado (Molas Pass to Wolf Creek Pass). Due to some possible unknowns, my resupply duration was 10 days, which meant about 20 lbs of food. Base pack weight is typically 17, add some water stretches and the first few days I loaded my Ultra Circuit right at 40 lbs; yeah I know the site says 35 lbs max, but I’m a glutton for punishment. But, I get ahead of myself.

    I’ve been holding out on a ULA pack for the past several years as I have been waiting for ULA to offer enhanced/modern materials and alas in 2023, they released the Ultra line! Despite my gut telling me to go with ULA, I did my due diligence and tried another manufacturer (something with Six in the name), and after some shakedowns, I just couldn’t get that pack to work with me. I returned it and promptly put my Ultra Circuit order into ULA. Peter got me a on a quick turnaround since my CDT trip was less than a few weeks away. I got the pack quickly (+stash pocket +shoulder pocket) and immediately upon seeing it and putting it on, I knew this pack was meant for me. A+ for customer service. A+ for fit, feel, fabrics, and workmanship. A+ for design and aesthetics.

    Back to the story of 40 lbs in the Circuit… well, it handled really well and carried great; I was blown away. I know I shouldn’t have loaded it that heavy but desperate times call for desperate measures, right?! Once I burned through food and got it down to 35, it felt like a dream, and as the load got lighter and lighter, it kept feeling better. So, don’t be scared in case you have to go over 35 lbs, but just know it does put quite a bit more stress into the pack, so I wouldn’t make this a habit myself.

    For everything else in/on the pack, it was all good…. everything was purposeful and well designed. Now I know why ULA stands by their designs while other manufacturers constantly are tweaking and changing things. ULA has knocked it out of the park and I completely understand why their packs consistently make the trail gear top lists.

    Nice on ULA!

  2. Kenneth Andrews

    Love this pack. Purchased it to replace my Osprey Atmos . I wanted a lighter pack that was the was the same liter capacity with a more minimalistic design. This pack is comfortable on the hips and shoulders. Carries well without the feeling of being enveloped by it as it sits on your back not around your sides. Have not put more than 28 pounds in it but I feel even slightly more 35 and it would still carry well. I did purchase this pack at an outfitter about an hour and a half drive from me. When I got it home I found the cord locks were not locking. I did try to figure out how to fix it but to no avail. Rather than drive back to the outfitter I emailed customer service about it. They got back to me the next day requesting a picture of the type lock it had as there are 2 types. Next day got the the instructions on how to set the lock as it was not done at the factory. I felt like an idiot as the solution was to just squeeze them until you hear and feel a click, yes I tried it but not hard enough. So customer service was excellent and prompt. I have roughly 200 miles with this pack and my only regret is I did not purchase this pack first. I finally convinced my wife to get one and on her first trip out with it she loved it. If your looking for a new pack without all the bells and whistles that is well made and carries well this is the pack for you.

  3. Connie DePaepe

    Best Pack & Customer Service ever.

    I started my 2022 PCT thru hike with another highly touted ultralight company. But, at the getgo I had issues. My journey trying to reach this highly touted other company were just the begining of an excruciating experience for resolution to my backpack issues. Trying to reach this other company to help with backpack problems was a nightmare. I hiked hundres of miles, taking multiple zeros just trying to reach this company. The money I spent waiting to reach someone and or for a call back was tremendous. To make matters worse only one customer service rep cared about helping and getting product shipped to me, yet after paying for a hotel for a week waiting for my fix, and paying extra for expedited shipment for a part I needed due to product failure, that never arrived, and being told by that company that I would not be refunded for non receipt..etc..etc… I threw my hands up. I really tried to like this other company. But, they made it impossible. Talking with other hikers who had the same experience, we all summized that this other company was only in it for the money.

    Then while in a hostel I discovered the ULA Circuit backpack.

    Most of the women at the hostel I was staying at, because I was ready to go home because I could not hike any further with my failed backpack, had the ULA Circuit backpack. I looked around the full hostel, everyone but me had the ULA Crcuit. I told them about my frustrations. They encouraged me to try on their ULA Circuit packs, which I did. What a game changer. Immediately, I could see what comfort felt like. I called ULA and actually spoke to someone on my first call!!!!

    I think the person’s name at ULA who helped me was Peter. I am 5’1″ tall and have a 17″ torso. At 110 lbs I was concerned about the fit. Not only did Peter walk me thru ordering my new pack, my new pack arrived the NEXT DAY. And I got a call from ULA the next day making sure everything was in working order.

    OH My goodness!!! What a difference.

    My ULA Circuit backpack made such a difference. My hiking experience improved 1000%. The customer service at ULA was over the top. ULA was a game changer.

    My ULA Circuit backpack fit beatifully. The shoulder straps sat on my shoulders perfectly, not with one side sliding off to one side like the other company’s pack. The hipbelt, so comfortable and if I need to swap out the hipbelt for a smaller one, easy peasy. The torso was also perfect. And being able to fit the bear can inside the pack..well, what more can I say. It was perfect.

    I did a lot of research prior to ordering my backpack and was confident I made the right choice with Zpacks Scout. The Scout is what Zpacks recommended based on my height, weight and torso. But, I was so wrong. The total weight on my pack out of gate was 24.6 pounds. The Scout was the only pack for my torso and yet it never fit, the stays broke, the hipbelt was a nightmare, the pack kept shifting from shoulder to shoulder. The pack never fit right, it never felt comfortable no matter what I tried and no matter what anyone else with pack experience could do to help. Trying to reach Zpacks and then get support made matters worse.

    For those with smaller frames who need a backpack that will enhance their journey, ULA is the company to contact and the backpack to purchase. Having the right backpack put me back on the trail rather than going home.

    I backpacked hundreds of miles close to 650 miles with a poorly built backpack resulting in great expense, pain and injury. I really wanted to love that Zpacks Scout backpack. In the end, based on my experience, I will never purchase a product from Zpacks again.

    Knowing now the pleasure of having a comfortable backpack and knowing if I have an issue I have a company who I can rely on, makes a huge difference.

    ULA is a great company. They are accessible, available, considerate, and make a great product.

    It is ULA all the way for this backpacker.

    Zpacks, that other company, who gets all the rave reviews from hikers on youtube…was a huge failure, in every category.

    ULA Circuit is the company to call when you need a backpack and a company with quality products, exceptional customer service and whose backpacks are of the highest quality. It is no wonder that the ULA Circuit is the most popular backpack the PCT.

    Thank you Peter for helping me when I called. I appreciate your attention and expertise.

  4. Dean Novitzke (verified owner)

    An incredible pack that I purchase recently for my 2023 PCT thru-hike. It is very adjustable for fit and comfort as well as allowing me to be very nimble with it on my back with load. It is probably one of the most durable packs out there yet very light weight at just a couple ounces over 2 lbs. This pack will carry everything needed plus food for the extend carry through the Sierra’s.

  5. Andrea Jasper (verified owner)

    This is a well-fitted, durable and lightweight backpack, I am so happy. It is more comfortable than other packs I have used because it is so customizable, it is not advertised as a women’s pack, but by choosing the ‘S’ straps and correct measurements, especially torso length, this pack fits me just right, unlike men’s or “unisex” packs that are designed to fit a man’s shaped body. The ‘S’ straps make all the difference, and I imagine this will be the case for most other women. Also, it is not super cushioned around the hips, but it is just enough. I didn’t have any discomfort or rubbing anywhere. The shoulder straps are sufficiently cushioned and wide enough without being too wide.
    Some people complained about not being able to reach a water bottle and put it back in the side pocket. I can get it back in without too much effort. And the elastic bands help hold water bottles in the side pocket so they don’t fall out when you bend over if they are adjusted tight enough…at least most of the time…I had them fall out occasionally when I really bent over.
    I did not find the back panel to be too sweaty, but I didn’t use it in real hot weather, either.
    The Ultra fabric is amazing, I have only had it on short trips so far, but I can see it’s going to hold up better than any other pack I’ve owned. It feels tough and abrasion resistant. I upgraded to the Dyneema stretch mesh pocket and am glad I did because I walk through a lot of sharp bushes and am always brushing along canyon walls. This pack will last me years and I will put it through its paces.
    The Ultra fabric is waterproof, and it does not absorb water and get heavy or sag when it’s wet. But the pack itself is not waterproof. I hiked all day in moderate to heavy rain/sleet/snow and some water did get inside and made a small puddle in the bottom of the pack. Most of my gear stayed dry enough. I also sank into quicksand crossing a river and submerged the pack a bit deeper than my waist for about 2 minutes. A couple drops of water got in, but not enough to get my gear wet. The hip pockets remained bone dry, the waterproof zipper on the pocket really works. But if you’re really taking your pack swimming or walking through a vigorous storm, it’s wise to waterproof the inside with plastic bags.
    The 68-liter capacity is perfect. I can roll the top down to keep it compact for easy trips with less gear, and it stores plenty of stuff on longer treks so I don’t have junk dangling on the outside. I occasionally guide backpacking trips and end up carrying a lot more gear than I would bring on a personal trip. I think the capacity will be enough for the guided trips.
    The panel that sits against your back is not very stiff, I can see if you overload the pack or shove a big, dense item in there it could create a lump against your back. Proper packing has not made this an issue for me. The pack carries weight well, but I can see it would probably be uncomfortable over maybe 30-35 pounds. It’s just not made for heavy loads like a framed, beefier pack. I just came back from a 3-night trip into the Grand Canyon with a total weight of 24.5 pounds and the pack felt fantastic at that weight. I wouldn’t want to carry much more than that anyway, and am trying to head the ultralight direction, vs. traditional framed packs that are overloaded. Leave the kitchen sink at home where it belongs and you’ll love this pack.
    I try to find made in U.S.A products and am proud this pack is not only made in America but right here in my home state of Utah. Thanks for making such a great pack.

  6. Stephen Yadzinski (verified owner)

    Home from the first trip with this incredible pack — 3 nights in Capitol Reef in late December. The pack performed flawlessly through blowing snow and rain, keeping the down sleeping bag and jackets I brought to stay warm completely dry. My pack weight was 27 lbs leaving the car, and felt very good and balanced at the start and throughout the trip. I have nothing but great things to say about this pack. I expect this to be my go to for many years to come. HIGHLY recommend!

  7. Gerald F. Chew

    I’ve moved from an X-PAC Circuit to the Ultra Circuit. Why you might ask? I’m a bit of a gear junkie, . . . and I have a lot of backpacks from various manufacturers; too many according to my wife. After “dialing” in the ULA pack they are by far the most comfortables ones that I own. While I absolutely love the X-PAC Circuit (i.e., I don’t think you can go wrong with either one or the Robic for that matter) which I used on the JMT, the Ultra Circuit is absolutely beautiful and actually seems more durable than the X-PAC. The Dyneema stretch mesh is incredible. This will now be my go-to pack.

    The gear aside, the absolute best thing about ULA is their customer support and service. I’ve spent hours with them on the telephone and e-mail messages discussing how I will use the pack, where, time of year, . . . They are very helpful if you have any questions at all.

  8. Glen Moore (verified owner)

    Just finished my first trip with my new Circuit Ultra, 45 miles in the Sawtooth National Forrest. The pack performed flawlessly. My pack weight was 30 pounds (not ultralight). A couple of long days over several mountain passes but the pack felt great the whole way. Plenty of room for all my gear. Love the stretch panel on back for easy access to jackets sit pads etc. I’m very geeky about my pack squeaking or being noisy as I walk down the trail this pack never made a sound no squeaks. The shoulder straps and hip belt are very comfortable and have plenty of padding even with a heavy pack. I love it and highly recommend this pack. Ready for my nest adventure!!

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