A reader named Marcus emailed me last month with a question I get some version of almost weekly: “I want one adjustable kettlebell instead of a rack of six, but everyone online says adjustable bells feel wrong for swings. Is that actually true, or are people just repeating it?” Marcus had a single corner of a spare bedroom to work with and a hard ceiling on both budget and floor space. He’d narrowed it to two systems — the dial-driven Bowflex SelectTech 840 and the pin-loaded PowerBlock — and wanted to know which one wouldn’t feel like a science project the first time he tried to clean it.
That question gets at the real tension with adjustable kettlebells. A fixed cast-iron bell is a solved problem: it’s a smooth lump of iron that behaves predictably. The moment you make it adjustable, you introduce a mechanism, a wider or boxier body, and a different center of gravity — and how a brand handles those trade-offs is the entire ballgame. The Bowflex 840 and the PowerBlock take opposite approaches to the same problem, and the right pick depends a lot more on how you train than on which spec sheet looks prettier. This is the breakdown I sent Marcus, expanded.
If you’re still deciding whether adjustable is even the right route for you, our adjustable kettlebell roundup covers the wider field, including budget picks. This piece is the deep head-to-head between the two systems most people end up choosing between.
How to judge an adjustable kettlebell
Before pitting these two against each other, it helps to know what actually matters once the novelty wears off. Five things separate an adjustable kettlebell you’ll keep from one that ends up shoved under the bed.
Weight range and increments. This is the first filter and it’s where these two products diverge hardest. A bell that only spans a narrow band, or that jumps in big chunks, limits how you can progress. For pressing and getting-up work you want smaller steps; for swings and squats you can tolerate bigger jumps. Look at both the top and bottom of the range and the size of the gaps in between.
The adjustment mechanism. Every adjustable kettlebell makes a promise: change the weight in seconds, trust it to hold. Dials, pins, and lever-and-plate systems all deliver on that promise to different degrees. The question isn’t just speed — it’s confidence. A mechanism you don’t fully trust over your own head or behind your back during a swing will quietly cap how hard you train.
Shape and feel. A kettlebell lives or dies on its handle and its body. The handle window has to clear your hand (and a chalked, gloved, or two-handed grip), and the body has to sit against your forearm in the rack position without digging in. Adjustable bells are almost always boxier than a cast bell, and some handle it far better than others.
Durability and warranty. Kettlebells get dropped, swung, and occasionally bailed onto the floor. The mechanism is the failure point — plastic locking parts and selector pins take the abuse. Warranty length is a decent proxy for how much faith the manufacturer has in its own mechanism.
Price per usable pound. Adjustable kettlebells sell on the math: one purchase replacing a shelf of bells. But the headline price only matters relative to the range you actually get and how often you’ll use the extremes. A cheap bell you outgrow in two months isn’t cheap.
With those five lenses in mind, here’s how the two stack up.
Bowflex SelectTech 840: the dial-driven all-in-one
The Bowflex SelectTech 840 is the most recognizable adjustable kettlebell on the market, and it leans on the same selection-dial concept that made the brand’s SelectTech dumbbells a fixture in home gyms.
Range and adjustment
The 840 covers 8 to 40 pounds across six settings — 8, 12, 20, 25, 35, and 40 lbs. You set the weight by turning a dial on the base, which engages or releases weight plates inside the housing, and Bowflex’s spec sheet describes it as replacing six separate kettlebells. The dial is genuinely fast: there’s no pin to fish out, no plates to handle, just a turn and lift. For circuit-style training where you’re flowing between a heavy swing and a lighter press, that speed is the 840’s headline strength.
The catch is in the gaps. Going 12 to 20 is an eight-pound jump, and 25 to 35 is ten pounds. For ballistic movements like swings and cleans those steps are fine. For grinds — strict presses, Turkish get-ups, where two pounds genuinely changes whether you complete the rep — the increments are coarse, and the bottom end starting at 8 lbs is a touch high for true beginners or for delicate prehab work.
Shape, feel, and build
The 840 measures roughly 8.8″ long by 7″ wide by 12.5″ tall, and the body is the squared, shrouded shape you’d expect from a plate-and-housing design. The handle window is comfortable for one- and two-handed grips, and the overall balance is reasonable for swings once you accept that it will never feel like a perfectly round competition bell against the forearm. Owner feedback across retailer reviews is consistent on this: people who use it for swings, goblet squats, and general conditioning are happy; people expecting a competition-bell rack feel for high-volume snatch work are the ones who grumble.
Bowflex backs the 840 with a 2-year parts warranty, and it carries optional integration with the company’s JRNY app if guided workouts appeal to you (it’s a subscription, and not something I’d factor into the buying decision either way).
At a $149 list price, the 840 is the value leader of this pairing on paper. Worth noting for 2026 shoppers: Bowflex’s own site has periodically listed the 840 as temporarily out of stock, so availability through Amazon and other retailers is worth checking against the direct price. View on Amazon
PowerBlock Adjustable Kettlebell: the pin-loaded heavy hitter
PowerBlock built its name on dense, compact adjustable dumbbells, and the brand brings the same engineering philosophy to its kettlebell line. Rather than one do-everything bell, PowerBlock splits the range across two models, which is the single most important thing to understand before buying.
Range and adjustment
PowerBlock offers a 18–35 lb model and a 35–62 lb model. The lighter bell steps through 18, 22, 26, and 35 lbs; the heavier Pro 35–62 selects 35, 44, 53, and 62 lbs. Each model “replaces four kettlebells,” and the two together cover an 18-to-62-pound span in eight settings — a meaningfully heavier ceiling than the Bowflex tops out at. If your training is heading toward heavy two-handed swings, heavy goblet squats, or one-arm rows where 40 lbs is a warm-up, PowerBlock is the only one of the two that gets you there.
Adjustment is via a magnetic selector pin — insert the pin, lift, and the unselected plates stay behind. It’s the same idea as the brand’s dumbbells. The pin is fast and the magnet keeps it seated, though it’s one more loose part to track than the Bowflex dial, and pin systems in general ask you to pay a little more attention that you’ve fully seated the selection before you load it overhead.
Shape, feel, and build
The Pro 35–62 is impressively compact for its weight — roughly 8″ long by 5.5″ wide by 11.25″ tall — because steel is denser than the plate-and-shroud approach. PowerBlock also did something the others didn’t: it kept a consistent 32mm handle diameter (competition-standard territory) across the weight range, so the bell doesn’t feel chunkier in the hand as you go heavier. For anyone with smaller hands or anyone who cares about grip consistency between sessions, that’s a real, underrated advantage.
Construction is solid/cast steel, and PowerBlock backs it with a 5-year warranty — the longest of this pairing and a signal of confidence in the mechanism. The trade-off is price: the Pro 35–62 lists around $349, more than double the Bowflex, and you’re buying a narrower four-setting range per bell. Buy both PowerBlock models to match the Bowflex’s “one bell does it all” convenience and you’re well past $500.
This is the same density-and-durability-over-price calculus that shows up in PowerBlock’s dumbbell line — the same trade-off I dug into in our Ironmaster Quick-Lock vs PowerBlock Elite EXP comparison, if you want to see how the brand’s philosophy plays out with adjustable dumbbells too.
Head-to-head: where each one wins
Weight range. PowerBlock wins outright on ceiling and on increment count if you buy into the two-model system: 18–62 lbs across eight settings versus 8–40 across six. But Bowflex wins on single-purchase coverage — one 840 spans more of the beginner-to-intermediate range than either single PowerBlock model does. If you only want to buy one object, the 840 covers more ground; if you want the heaviest top end, PowerBlock is the only option here that reaches it.
Adjustment. Close, with a slight edge to Bowflex for pure convenience. The dial is one motion with no loose parts; the PowerBlock pin is fast but is a separate piece to seat and not lose. Both are quick enough that you won’t avoid changing weights mid-workout.
Feel and grip. PowerBlock takes this for anyone who values handle consistency, thanks to the fixed 32mm diameter and the denser, more compact body. The Bowflex is perfectly usable but boxier, and its handle is a typical adjustable-bell window rather than a competition spec.
Durability. PowerBlock, on the strength of its 5-year warranty and steel construction versus the Bowflex’s 2-year coverage.
Price. Bowflex, decisively, at $149 versus $349 for a single heavy PowerBlock. The value gap only narrows if you specifically need PowerBlock’s heavier ceiling or longer warranty.
Which should you buy?
For most home gym lifters — people doing swings, goblet squats, presses, and conditioning circuits in the 8-to-40-pound world — the Bowflex SelectTech 840 is the better first adjustable kettlebell. It costs less than half as much as the heavy PowerBlock, one unit covers the range a beginner-to-intermediate lifter actually uses, and the dial is the most frictionless adjustment of the two. The coarse increments and the 8-pound floor are real limitations, but they’re limitations most general trainees never bump into.
Buy the PowerBlock instead if you fit one of two profiles. First, if you already know you’re training heavy — if 40 lbs is your warm-up weight for swings and rows and you need to get to 50 or 60 — PowerBlock’s 35–62 model is the only bell in this comparison that gets you there, and the 5-year warranty and steel build are worth the premium for heavy ballistic abuse. Second, if grip consistency matters to you (smaller hands, or you’re particular about the handle feeling the same at every weight), the fixed 32mm diameter is a genuine, daily-felt advantage the Bowflex can’t match.
A quick note for true beginners and anyone on a tighter budget: both bells in this comparison sit at the higher end of the adjustable market. There are lighter, cheaper options — like the sub-$130 Titan 40 LB adjustable (10–40 lbs) or the lifetime-warranty Kettlebell Kings 10–40, both of which I cover in the full adjustable kettlebell roundup. If the Bowflex-vs-PowerBlock decision feels like more bell than you need, start there.
Whichever you choose, give a thought to where it lands when you set it down. A dropped adjustable bell is harder on a bare floor — and on the mechanism — than a cast bell, so a rubber mat under your training space is cheap insurance. And if you’re pairing the kettlebell with dumbbell or barbell work, our adjustable bench and weight guides cover the rest of a compact strength setup.
Frequently asked questions
Can you really do kettlebell swings with an adjustable kettlebell?
Yes. Both the Bowflex 840 and the PowerBlock are rated and built for swings, and owner feedback for both is broadly positive on ballistic work. The honest caveat is feel: adjustable bells are boxier than round cast bells, so the body sits against your forearm differently in the rack position and the swing arc feels slightly less “settled.” Most people adapt within a few sessions. If you’re doing high-volume competition-style snatching, a dedicated competition bell will still feel better — but for the swings, cleans, and goblet work the vast majority of home trainees do, an adjustable bell is entirely capable.
Is the Bowflex 840’s dial or the PowerBlock’s pin more reliable?
Both mechanisms are proven and both hold securely in normal use. The dial has no loose parts, which some people prefer; the pin is a separate magnetic piece you insert. The more relevant durability signal is the warranty: PowerBlock’s 5 years versus Bowflex’s 2 years suggests more manufacturer confidence in the long-term mechanism, though that gap also reflects the price difference. With either, the practical rule is the same — confirm your weight is fully selected before you lift, and don’t bail the bell onto a hard floor.
Why does the PowerBlock cost more than twice as much?
You’re paying for a heavier weight ceiling, denser steel construction, a competition-standard 32mm handle held consistent across the range, and a longer warranty. Whether that’s worth roughly $200 extra depends on your training. A lifter who needs 50–60 lbs and trains hard will feel the value; a general trainee living in the 8–40 range mostly won’t, which is why the Bowflex is the better-value pick for most people.
Can I match the Bowflex’s full range by buying one PowerBlock?
Not quite. A single PowerBlock model gives you four settings within either an 18–35 or a 35–62 band. To cover the same beginner-to-heavy span the Bowflex addresses (and then some), you’d buy both PowerBlock models, which pushes the total past $500. If single-purchase range is your priority, the Bowflex wins; if top-end weight is your priority, the PowerBlock is the only option that delivers it.
Are these worth it versus a set of fixed cast-iron kettlebells?
For space- and budget-conscious home gyms, usually yes. Buying the individual fixed bells to match either adjustable system’s range typically costs more and takes far more floor space. The adjustable trade-offs are the boxier shape and the mechanism as a potential failure point. If you have the room and the budget, a few fixed competition bells will feel better; if you’re fitting a gym into a corner, the adjustables earn their place.
Which is better for small spaces?
Both are far more compact than the rack of bells they replace, but the PowerBlock 35–62 is the more space-dense of the two, packing 62 lbs into a roughly 8″ x 5.5″ x 11.25″ footprint thanks to its steel construction. The Bowflex is slightly larger for its weight but still a single, stowable unit. For genuinely tight setups, also weigh how you’ll store and protect it — a single stowable bell and a small rubber mat is about as space-efficient as free-weight training gets.