CORE Backpack Medium 25L
Man wearing black CORE Backpack in gym
Black CORE Backpack with matching lifting belt sitting on wooden box
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Black CORE Backpack sitting on wooden box
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Internal of CORE Backpack packed with lifting belt, drink bottles and workout gear
Shaker inside black CORE Backpack bottle pocket
Sneakers inside black CORE Backpack shoe compartment
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Side by side comparison of large and medium CORE Backpack
Side by side comparison of large and medium sized CORE Backpack
CORE Backpack Medium 25L
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CORE Backpack Medium 25L

4.8
Rated 4.8 out of 5 stars
4.8 Stars (273 Reviews)
$150 $170
Size: Medium 25L
Mini 13L
Mini 13L
Medium 25L
Medium 25L
Color: Black
Black
Natty
Limited Edition - Waxed Canvas:
Tan
Black
Traditional
Camo
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Matching Lifting Belt
Matching Lifting Belt
$50 $60
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BUILT FOR LIFTERS & SERIOUS ORGANIZATION

  • External weightlifting belt attachment
  • 16” Internal laptop sleeve
  • Sealed internal shoe compartment
  • Dual bottle pockets 

Do you even lift? If so, meet your new training partner. Say goodbye to your belt wasting space inside your bag, with this unique and specially designed lifting belt attachment that ensures bag functionality isn’t compromised whatsoever. The CORE Backpack is made for those who train hard and pack smart. 

(Lifting belt sold separately)

Covered by our guarantee to be free of defects in material or workmanship. If there is a defect in materials or workmanship KNKG will repair or replace your bag.

Our bags are meticulously designed to stand up to the test of time. We utilize durable materials, coupled with top-notch craftsmanship and rigorous testing, resulting in the toughest bags in the game. You can confidently pack your bag to its maximum capacity without worrying about it stretching or tearing.


The CORE Backpack is made from:

• 500D nylon body material (PVC backing)

• YKK zippers

• Ripstop nylon lining

• Nylon webbing

​
CORE BACKPACK
SIZE COMPARISON
Capacity
Bag Weight
Height (H)
Width (W)
Depth (D)
Shoe Storage
Laptop Sleeve
MINI
13 L / 3.4 GAL
0.8 kg / 1.8 lbs
35cm / 13.8"
25cm / 9.8"
15cm / 5.9"
Not recommended
iPad
MEDIUM
25 L / 6.6 GAL
1 kg / 2.2 lbs
50.8cm / 20"
30.5cm / 12"
17cm / 6.7"
Up to size 10
Up to 16"
LARGE
33 L / 8.7 GAL
1.1 kg / 2.4 lbs
53.3cm / 21"
31cm / 12.2"
20.1cm / 7.9"
Up to size 13
Up to 16"
Capacity
Bag Weight
Height (H)
Width (W)
Depth (D)
Shoe Storage
Laptop Sleeve
MINI
13 L / 3.4 GAL
0.8 kg / 1.8 lbs
35cm / 13.8"
25cm / 9.8"
15cm / 5.9"
Not recommended
iPad
MEDIUM
25 L / 6.6 GAL
1 kg / 2.2 lbs
50.8cm / 20"
30.5cm / 12"
17cm / 6.7"
Up to size 10
Up to 16"
LARGE
33 L / 8.7 GAL
1.1 kg / 2.4 lbs
53.3cm / 21"
31cm / 12.2"
20.1cm / 7.9"
Up to size 13
Up to 16"

This backpack is designed for serious lifters who crave serious organization.

This gym bag works harder than you do. This is the best and most functional gym bag you can find.

This is the best gym bag for powerlifters. Many amazing features that set this bag apart from its rivals. The outer material is tough, durable, and lightweight while also being water resistant and easy to clean.

FAQS

The main difference is the unique weightlifting belt attachment. This feature allows the bag be used as normal, while carrying a cumbersome lifting belt on the outside. Other changes are the volume (25L and 33L) and the layout.

Most of the materials are the same as used in other KNKG bags. YKK zippers, heavy duty buckles, nylon lining and webbing are all the same. In the CORE range, we have gone for a lighter 500D nylon outside and a new velcro logo feature that allows you to go 'incognito' with your own patches.

Measure the widest point of your belt. The CORE33 (Large) Backpack can fit a belt up to 6.3"/16cm wide. The CORE25 (Medium) Backpack can fit a belt up to 5.9"/15cm wide.

And yes! Lever belts will work with this bag.

The CORE25 (Medium) Backpack fits shoes up to size 10 US mens trainers/runners comfortably. The CORE33 (Large) Backpack fits up to size 13 US mens.

4.8
Rated 4.8 out of 5 stars
Based on 273 reviews
96%would recommend these products
Slide 1 selected
273 reviews
  • JC
    Joshua C.
    Verified Buyer
    Reviewing
    CORE PRO Backpack Large 33L
    I recommend this product
    Rated 5 out of 5 stars
    Great for Commuting Military

    I’ve been really happy with this backpack for my day-to-day commute to the Pentagon. It has plenty of room without feeling overly bulky, and I can comfortably fit my lunch box, gym gear, and other daily essentials inside. One of the biggest positives for me is that it also meets military uniform requirements, so I can carry it while in uniform without worrying about compliance. It’s comfortable, practical, and has been a great all-around commuter bag. Definitely recommend it for anyone looking for a solid work and gym backpack.

    Was this helpful?
  • EA
    Ethan A.
    Verified Buyer
    Reviewing
    CORE Backpack Medium 25L
    I recommend this product
    What type of training is your KNKG bag supporting you with? Weightlifting, Other
    Using For: Gym Bag, Every Day Carry, Sport / Fitness
    Rated 4 out of 5 stars
    Great size and highly durable

    The medium 25L bag feels like a standard sized backpack. Has a good amount of pockets with plenty of room. It's a very durable bag. I also love the Belt holder. My only complaint is that since I have a small waist, my smaller belt makes using said room and pockets slightly harder to access when my belt is on the belt holder.

    Was this helpful?
  • JR
    Johnny R.
    Verified Buyer
    Reviewing
    CORE Backpack Large 33L
    I recommend this product
    What type of training is your KNKG bag supporting you with? Weightlifting, Bodybuilding
    Using For: Every Day Carry, Sport / Fitness, Gym Bag
    Rated 5 out of 5 stars
    Great!

    Solid fit for the gym spacious and lots of compartments for your gym accessories!

    Was this helpful?
  • J
    Jonathan
    Reviewing
    CORE Backpack Waxed Canvas Medium 25L
    I recommend this product
    Rated 5 out of 5 stars
    5 Stars

    This thing is perfect. Wish you made this in large with waxed canvas. I bought the waxed mini duffel as well and love them both.

    Was this helpful?
  • JG
    Justice G.
    Verified Buyer
    Reviewing
    CORE PRO Backpack Large 33L
    I recommend this product
    Rated 5 out of 5 stars
    Durable, spacious, well designed

    As always, KNKG has knocked it out of the park. The redesign keeps all of the best aspects of the CORE bag, while streamlining small but meaningful features such as the top pocket, and the side waterbottle pockets. Also, the expanded velcro patch area is fun.

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Ultimate Gym Backpack with Weightlifting Belt Attachment — KNKG CORE Backpack

The CORE Backpack is purpose-built for lifters who want the convenience of a backpack with the functionality of the iconic weightlifting belt attachment. Designed for the gym, not the office, this pack carries everything you need for serious training sessions — and keeps your lifting belt secure on the outside so the inside stays free for the rest of your gear.

Why the Weightlifting Belt Attachment Matters

Lifting belts are bulky, and most backpacks aren’t built to carry them. Forcing one inside means less room for your gear. The CORE Backpack solves this with an external weightlifting belt sleeve that gives gym rats the freedom to pack properly:

  • Save Space: Belt stays outside, leaving the main compartment free.
  • Secure Fit: Reinforced sleeve and straps keep your belt secure while you move.
  • Quick Access: Pull out your belt instantly when it’s time to lift.
  • Backpack Convenience: Carry comfortably whith padded shoulder straps and a breathable back pannel.

What Fits Inside

The CORE Backpack is designed for the gym. Here’s what you can fit inside:

  • Weightlifting shoes or sneakers (dedicated shoe compartment)
  • Change of training clothes
  • Shaker bottle or water bottle (side pockets)
  • Chalk, straps, wraps, and grips
  • Knee sleeves or elbow sleeves
  • Towel
  • Headphones, small tech, or training electronics
  • Snacks or post-workout supplements
  • Phone, wallet, and keys (internal valuables pocket)

With your belt carried externally, the backpack’s interior compartments are left open for everything else you need for heavy training.

Materials & Build

  • 500D nylon body material with PVC backing
  • Ripstop nylon lining
  • Heavy-duty YKK zippers
  • Reinforced nylon webbing straps and handles

The Toughest Gym Bag Quality

Like the CORE Duffel, the CORE Backpack is built to thrive under tough conditions. Reinforced stitching, abrasion-resistant nylon, and metal hardware mean it’s made to last through years of training sessions, travel, and gym-floor abuse.

Why Choose the CORE Backpack?

  • Unique external weightlifting belt attachment
  • Purpose-built for weightlifters — not your average everyday carry backpack
  • Smart compartments: shoe zone, valuables pocket, side bottle holders
  • Built from premium, abrasion-resistant materials for unmatched toughness