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1 19
Customers rate us 5.0/5 based on 2789 reviews.

40kg Adjustable Dumbbell (Pair)

£279.99 £499.99
  • Easily shift from 5kg to 40kg
  • Pair of 17-in-1 Adjustable Dumbbells
  • Simply turn the dial to change the weight
  • 24 Months Warranty
🚚 FREE avg next day delivery
🛡️ 2-YEAR warranty on all dumbbells
😊 Over 75,000+ happy customers
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Free & Fast UK Delivery

We offer FREE Standard Delivery to England, Scotland & Wales on ALL orders.

Express Delivery is available for a small surcharge. All other orders will be subject to additional delivery charges.

Standard Delivery will take 2-4 business days, however we aim to dispatch all orders as soon as possible.

See our Delivery Information page here.

Why choose BRAINGAIN
  • Rated Excellent on Trustpilot, over 1000 5* reviews!
  • Over 50,000 Adjustable Dumbbells sold.
  • UK’s leading Fitness & Home Gym Brand.
  • Spread the cost with Klarna or Clearpay.
  • 2 Years Warranty on everything.

Overview

Easily shift from 5kg to 40kg with the innovative BRAINGAIN 40kg Adjustable Dumbbells which are perfect for home workouts whether you’re training in your garage, the back garden or your living room. One pair of these adjustable dumbbells replaces a complete set of 17 fixed dumbbells saving you space, cost and time!

The BRAINGAIN 40kg Adjustable Dumbbells are perfectly designed and quality tested to ensure the highest level of safety for all users whether you are a beginner training for the first time or a professional with years of experience. Simply twist the dial on each side of the adjustable dumbbell to set the weight, pick up your weights and you can start training straight away and are a real evolution from the old style, spinlock style adjustable dumbbells.

Adjustable Dumbbells can be used for all your home workout needs and exercises including presses, swings, deadlifts, squats, curls, sit-ups, snatch, renegade row, twists, clean & press, thrust and more.

The 40kg Adjustable Dumbbells come with their own tray to facilitate simple weight changes and tidy storage. Separate stands can be purchased to bring the adjustable dumbbells up to waist height.

The Adjustable Dumbbells are designed to stay with you on your journey. Whether you’re starting on the lightest weight, or something heavier, the adjustable weights will be by your side as you gain strength and go through the weight range.

Features

The BRAINGAIN 40kg Adjustable Dumbbells is the equivalent to 17 individual fixed weight dumbbells. Increments: 5kg, 7kg, 9kg, 11kg, 13kg, 15kg, 18kg, 20kg, 22kg, 25kg, 27kg, 29kg, 32kg, 34kg, 36kg, 38kg, 40kg.

Dimensions: 45cm x 25cm x 25cm

Please note: dumbbells are sold as a pair, representing 2x 40kg so 80kg total

Warranty

All of our products come with a 24 month warranty as standard. We offer extended warranty options on selected products which if available will be shown above the 'Add to Cart' button above.

“For the most experienced iron-pumpers, while perfectly catering to beginners too.”

“The build quality is excellent. The knurled metal handle is the icing on the cake.”

“An industrial-strength set of weights with a smart design.”

“Robust... and comfy for most classic moves.”

“Ultra smooth and easy to twist... one of the sturdiest designs we tried.”

  • Turn of a dial

    Easily shift from 5kg to 40kg with the innovative BRAINGAIN 40kg Adjustable Dumbbells. No more need for 17 seperate weights.

  • Base or Stand

    The 40kg Adjustable Dumbbells come with their own tray to facilitate simple weight changes and tidy storage. Separate stands can be purchased to bring the adjustable dumbbells up to waist height.

  • Total Body Workouts

    Adjustable Dumbbells can be used for all your home workout needs and exercises including presses, swings, deadlifts, squats, curls, sit-ups, snatch, renegade row, twists, clean & press, thrust and more.

Your Body Is Already Losing Muscle

From age 30, your body naturally loses muscle mass. Without resistance training, it only gets worse.

3-5%

muscle mass lost per decade from age 30. After 50, this accelerates to 1-2% per year.1

10-17%

lower risk of all-cause mortality, cardiovascular disease and diabetes from strength training.2

30-60 min

per week is the optimal dose - just 3x 20-minute sessions for maximum longevity benefit.3

1 Source 2 Source 3 Source

Built Different. Here's the Proof.

We surveyed 659 BrainGain customers across 5 key markets.

90%

said the value justified the price or price wasn't even a concern.*

72%

train 3 or more times per week with their BrainGain dumbbells.*

81%

want to buy more BrainGain products (accessories, supplements, training).*

* Source: BrainGain Customer Survey, February 2026, n=659 across 5 markets.


Rated Excellent on Trustpilot

Don't just take our word for it. Over 1,800 verified reviews from real customers.

★★★★★

Really Happy!

Dean Moran

Really happy with these adjustable weights, easy to put together and smoothly changes weights from 2.5kg all the way up to 40kg.

★★★★★

I previously was using the 24kg

Lee Philpott

I previously was using the 24kg dumbells which are still going strong but have upgraded to the 40kg octagon dumbells, good quality dumbells and look amazing.

★★★★★

Great Quality 40kg Dumbbells

Stephen Hammond

They are great quality and very between 2.5 to 40kg. Perfect for my home gym setup. Quality and ease of use is 10/10 saves so much space and work really well for both me and my girlfriend.

TrustPilot Read all reviews →

DIMENSIONS

Length: 46cm

Height: 21.5cm

Width: 23.5cm

"Game-Changer for Home Workouts!"

These adjustable dumbbells are a fantastic addition to my home gym. The Smart Click technology makes switching weights super easy, and the stand keeps everything neat and accessible. Highly recommend!

Liam Stafford - Manchester

Product Highlights

Explore the key features of our 40kg Adjustable Dumbbell (Pair) by clicking on the pulsing highlights.

Us vs. Them

Not overhyped or overpriced.
Just premium adjustable dumbbells built to last.

BrainGain
Generic Adjustable
Gym / Fixed Weights
Max weight
Up to 40kg
24-40kg
Depends on gym
Weight settings
17 per dumbbell
8-12
Fixed
Change weight in 1 sec
No rattle during lifts
Replaces entire rack
2 year warranty
Premium support