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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Flat lay of gym gear that packs inside CORE Backpack
Black CORE Backpack sitting on wooden box
Side view of black CORE Backpack
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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 (291 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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Want the PRO version? Check out the new CORE PRO Backpack →

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 291 reviews
96%would recommend these products
Slide 1 selected
291 reviews
  • JN
    Jennifer N.
    Verified Buyer
    Reviewing
    CORE Backpack Mini 13L
    I recommend this product
    What type of training is your KNKG bag supporting you with? CrossFit
    Using For: Gym Bag
    Rated 5 out of 5 stars
    CORE Mini Backpack

    Perfect size & great quality!

    Was this helpful?
  • SA
    Scott A.
    Verified Buyer
    Reviewing
    CORE PRO Backpack Mini 13L
    I recommend this product
    Rated 5 out of 5 stars
    Best Gym Bag

    KNKG has the best bags. This is my second and I use both for the gym. Durable, and there is a place for everything and easy to find.

    Was this helpful?
  • SR
    Steven R.
    Verified Buyer
    Reviewing
    CORE Backpack Medium 25L
    I recommend this product
    What type of training is your KNKG bag supporting you with? Weightlifting
    Using For: Gym Bag
    Rated 5 out of 5 stars
    Perfect Gym Bag

    This has become my perfect gym bag. Easily carries whatever I need for that day, even on leg day when I carry my lever belt, knee sleeves, shoes, and more. Enough space and structure in the main compartment and the smaller area are perfect for the other things you need (air pods, lock, keys and wallet, tape). So glad I pulled the trigger on this bag. Worth every penny.

    Was this helpful?
  • J
    Juan
    Reviewing
    CORE Backpack Mini 13L
    I recommend this product
    Rated 4 out of 5 stars
    4 Stars

    Good bag, slight QC issue

    Works great for what I need it for! Only giving 4 stars because one of the zipper pulls came loose upon arrival. Otherwise, no complaints.

    Was this helpful?
  • NH
    Nicholas H.
    Verified Buyer
    Reviewing
    CORE Backpack Waxed Canvas Mini 13L
    I recommend this product
    Rated 5 out of 5 stars
    Compact and stylish

    Originally bought this for the gym, but the moment I opened the box I decided it was far too nice for that. It’s beautifully made, the material feels rugged but still looks refined, and the smaller size suits me really well. Easy 5/5 one sexy bag. The only downside is that the material(waxed canvas) seems to pick up dust fairly easily, but that’s more about the fabric than the bag itself.

    Was this helpful?
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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