Choose adjustable dumbbells by mechanism first, then by top weight and footprint. A dial system such as the Bowflex SelectTech 552 changes weight fastest, a selector-pin block such as the PowerBlock Sport 24 is the most compact, and plate-loading is simplest but slowest. Match the top weight to what you will lift in a year.
This guide draws on the makers' own specification pages and NHS guidance. It does not involve testing, because the site does not test products.
What are the three types of adjustable dumbbell?
Adjustable dumbbells use a dial, a selector pin or loose plates with a collar. The mechanism decides how quickly you can change weight between exercises, and it is the biggest difference in daily use.
- Dial: you twist a dial at each end and the dumbbell picks up the weight setting you chose. Bowflex describes its 552 as having quick adjustment weight selection dials, switched "with a quick twist of the dials".
- Selector pin: you slide a pin into the slot that matches the weight you want. PowerBlock describes a secure magnetic pin on the Sport 24, with one pin per dumbbell.
- Plate-loading: you slide plates onto a handle and lock them with a collar. This is mechanically the simplest, and it takes the longest to change, because plates are added and removed by hand each time.
For a head-to-head of two dial and pin designs, see the Bowflex vs PowerBlock adjustable dumbbells comparison.
How much weight do you need from adjustable dumbbells?
Pick a top weight you expect to reach within a year of regular training, because adjustable systems cannot always be expanded. Bowflex lists the 552 at 5 to 52.5 lb per dumbbell (2.3 to 23.9 kg), and its UK 1090i page states 4 to 41 kg.
PowerBlock lists the Sport 24 at 3 to 24 lb per dumbbell, about 1.4 to 10.9 kg. The maker says it cannot expand past 24 lb per hand and that Sport EXP expansion kits are not compatible, pointing heavier lifters to other models in its range.
That ceiling is fine for lighter work such as curls and raises, but may be outgrown quickly on presses and rows. The dumbbell weight guide for beginners explains how to choose starting loads.
How do the common adjustable dumbbells compare?
The figures below come from each maker's own page. Prices are indicative and dated; the Bowflex 1090i price in our data covers a single dumbbell, so it is not shown here.
| Model | Mechanism | Weight range per dumbbell | Settings | Dimensions (L x W x H) |
|---|---|---|---|---|
| Bowflex SelectTech 552 | Dial | 2.3 to 23.9 kg (5 to 52.5 lb) | 15 | 43 x 21.2 x 22.8 cm |
| Bowflex SelectTech 1090i | Dial | 4 to 41 kg per the UK page | 15 or 17, the page lists both | 44.4 x 24.2 x 25.3 cm |
| PowerBlock Sport 24 | Magnetic selector pin | About 1.4 to 10.9 kg (3 to 24 lb) | 8, in 3 lb steps | About 25 x 14 x 14 cm (10 x 5.5 x 5.5 in) |
Bowflex's UK 1090i page is not consistent. It states 17 weight increments in the description and 15 settings in the specifications, and its specification table lists the 552's weight range. Confirm the figures with the seller before you order.
How much space do adjustable dumbbells need?
Check the footprint of one dumbbell, because you will need room for two plus a place to rest them. The Bowflex 552 is listed at 43 x 21.2 x 22.8 cm per dumbbell and the 1090i at 44.4 x 24.2 x 25.3 cm.
The PowerBlock Sport 24 is the smallest of the three at roughly 25 x 14 x 14 cm, which is why it suits a shelf or a small room. PowerBlock lists a grip length of 4.88 in and a grip diameter of 32 mm, so check that the grip suits your hand.
Bowflex lists storage trays as included with the 552, and says a stand is compatible but sold separately. If floor space is the limit, the small apartment home gym setup guide covers layouts.
Are adjustable dumbbells worth it over fixed ones?
They are worth it when space is tight and you want many weights from one pair. They cost more than a single fixed pair, but one Bowflex 552 offers 15 settings and one PowerBlock Sport 24 offers eight selectable weights, which would otherwise be 15 or eight separate dumbbells. The 552 is around £608 (checked Oct 2026) and the Sport 24 around £205 (checked Oct 2026).
Fixed dumbbells are quicker to grab and have no mechanism to fail. Our adjustable vs fixed weight dumbbells guide sets out the trade-offs, and the best adjustable dumbbells UK guide compares specific models.
What should you check before you buy?
Read the maker's page for the warranty, the step size and the handling guidance. Details that vary are easy to miss.
- Step size: Bowflex steps the 552 in 2.5 lb jumps up to 25 lb, then 5 lb. PowerBlock uses 3 lb steps on the Sport 24. Smaller steps help you progress gradually.
- Warranty: Bowflex lists 2 years on parts as standard for the 552, with accidental damage covered only under optional protection plans. PowerBlock lists a 5 year limited warranty for residential use only.
- Tolerance: Bowflex notes that individual weight settings may vary from their stated values because of manufacturing tolerances.
- Dropping: the Bowflex page gives no guidance on dropping the dumbbells, so lower them under control and use flooring that protects both the floor and the equipment.
Read the individual Bowflex SelectTech 552 review and the PowerBlock Sport 24 review for what each maker states in more detail.
What does the NHS say about strength training?
The NHS says adults aged 19 to 64 should do strengthening activities that work all the major muscle groups on at least two days a week. It names legs, hips, back, core, chest, shoulders and arms, and lists lifting weights as an example.
Adjustable dumbbells suit that because one pair can cover light and heavy work across the body. If you have a health condition or are new to lifting, speak to a GP or a qualified professional first, and follow the maker's instructions for safe use.
