Adjustable vs fixed dumbbells comes down to space and the number of loads you need. An adjustable set puts several loads in one pair, while fixed pairs suit a room with space and a few set loads. The two adjustable sets compared here stop at a top setting of about 24 kg per hand.
This guide uses published maker specifications and indicative prices. It is research-based, and the site does not test products.
Are adjustable dumbbells worth the extra cost?
They can be when floor space is limited, because one pair replaces several fixed pairs, but the saving is in space rather than money. PowerBlock says its Sport 24 replaces 8 pairs of traditional dumbbells, and Bowflex says its Results Series 552 replaces 15 sets of weights. The indicative prices here, around £205 and around £608 (both checked Oct 2026), are higher than a single fixed pair.
| Model | Range per dumbbell | Settings | Size per dumbbell | Warranty (maker page) | Indicative price |
|---|---|---|---|---|---|
| PowerBlock Sport 24 | 3 to 24 lb (about 1.4 to 10.9 kg) | 8, in 3 lb steps | 10 x 5.5 x 5.5 in (about 25 x 14 x 14 cm) | 5 years limited, residential use only | around £205 (checked Oct 2026) |
| Bowflex Results Series 552 | 2.3 to 23.9 kg | 15 | 43 x 21.2 x 22.8 cm | 2 years, parts only | around £608 (checked Oct 2026) |
| Fixed rubber hex pair (PROIRON 14kg listing) | Not published | 1 | Not published | Not published | around £90 (checked Oct 2026) |
The Bowflex 552 page refers to the Results Series model sold on bowflex.com. Bowflex's UK site may list a different 552 variant, so check the exact model before buying. Our PowerBlock Sport 24 review and Bowflex SelectTech 552 review give the detail on each set.
How do the two adjustable sets change weight?
They use different mechanisms: the PowerBlock Sport 24 uses a magnetic selector pin and the Bowflex 552 uses quick-adjustment dials. PowerBlock describes its pin as secure and its welded steel plates as smooth and quiet. Bowflex describes metal components and a locking mechanism that hold the plates to the handle. The maker pages do not compare speed or ease of use, so those are not claimed here.
The handles also differ on paper. The Sport 24 has a contoured TPR (rubber) grip, 32 mm in diameter, and PowerBlock states that no knurled handle is offered. Bowflex lists a non-slip grip on the 552.
What is the main limit of adjustable dumbbells?
Every adjustable set has a top setting, and the two compared here stop at about 24 kg per hand or sooner. PowerBlock states that the Sport 24 does not expand beyond 24 lb per hand and that its Sport EXP kits are not compatible. Bowflex's 552 stops at 23.9 kg per dumbbell. Bowflex also notes that individual weight settings may vary from their stated values because of manufacturing tolerances.
If you expect to need heavier loads soon, a higher-range set such as the Bowflex 1090 line (10 to 90 lb, or 4.5 to 40.8 kg, on bowflex.com) is a different class. Our 1090i review covers it, including conflicting figures on the UK page.
Warranty terms differ too. PowerBlock's warranty on the Sport 24 is limited and residential only. Bowflex's standard warranty on the 552 page is 2 years and covers parts only, with paid Protection+ plans offered as extensions.
Do fixed-weight dumbbells need a rack?
No maker requires one, but each load needs its own pair, so storage grows as you add pairs and a rack or shelf is a sensible way to organise them. A fixed dumbbell has one load and no moving parts. The data for this site includes two fixed rubber hex examples, a PROIRON pair and an Exersci pair, but neither brand has a maker page that could be opened, so their weights, dimensions and warranties are not quoted here. The PROIRON listing carries an indicative price of around £90 (checked Oct 2026). There is no price for the Exersci pair.
Reasoning from the design rather than from a spec sheet: the range you can train with grows only as you add pairs, and each pair adds to what you must store. A single fixed pair at around £90 costs less than the PowerBlock at around £205, but the adjustable set holds eight loads. The comparison depends on how many different loads you will use.
Which suits which situation?
The answer follows from your space, your budget and the loads you expect to use.
- Small flat or shared room: an adjustable set takes the floor area of a block or two trays rather than a rack. See small apartment home gym setup and home gym storage ideas.
- Dedicated garage or spare room with a rack: fixed pairs avoid the mechanism and the top-setting limit, as long as you budget for the pairs you need.
- Only one or two exercises at a fixed load: one or two fixed pairs may be enough, which keeps the cost down.
- Many exercises, each needing a different load: an adjustable set covers more loads per square metre.
- Heavy lifting beyond about 24 kg per hand: the two sets in the table stop there or sooner, so look at a higher-range set or fixed pairs.
A practical way to decide is to list the exercises you plan to do and the load you expect for each. If the loads fall inside one set's range and you are short of floor area, adjustable is the more space-efficient route. If you expect only two or three distinct loads, or you already have a rack, fixed pairs remove the mechanism and its range limit. Second-hand fixed pairs are also an option; see second-hand home gym equipment.
What to check before you buy
- Top and bottom settings, and the step between them. Bowflex's 552 settings are not evenly spaced: 2.5 lb steps at the low end, then 5 lb steps from 25 lb, with a top setting of 52.5 lb. PowerBlock's steps are an even 3 lb.
- Size of each dumbbell, not just the set. The Bowflex 552 is 43 cm long per dumbbell, per the maker. The PowerBlock block is 10 inches long.
- Whether a stand is included. PowerBlock's Sport 24 page states no stand is included. Bowflex lists storage trays with the 552 and sells its SelectTech stand separately.
- Warranty scope, including the residential-only condition on the PowerBlock.
- Delivery and returns. The PowerBlock page describes shipping within the contiguous US only, and the Bowflex 552 page describes US offers, so UK delivery and returns terms come from the UK seller. GOV.UK business guidance says customers who order online can cancel up to 14 days after delivery without giving a reason. Check the seller's own terms too.
- The surface underneath. See home gym flooring for options.
Who should skip adjustable dumbbells?
Buyers with ample space and a plan for a few set loads may find fixed pairs simpler. Buyers expecting to lift well beyond 24 kg per hand will outgrow both sets in the table. Buyers who want the lowest outlay and only one or two loads gain little from a set priced at several times a single pair.
How much strength training do UK adults need?
The NHS guidelines for adults aged 19 to 64 say to do strengthening activities that work all the major muscle groups on at least 2 days a week, and name lifting weights as one example. Either dumbbell type can meet that. Ask a qualified professional about what is suitable for you.
If you are weighing dumbbells against other first purchases, read kettlebell vs dumbbell training, and for models compared side by side see adjustable dumbbells in the UK. For loading and safety questions, follow each maker's instructions and ask a qualified professional.
