Just about every weight lifting enthusiast wants to improve the size and appearance of their biceps muscle. And who can blame them? The biceps are one of the most visible muscles on the human body, and it's always the one that people ask you to flex.
We sought to answer this question by explaining the key differences between these two popular exercises and then discussing which one is the most effective.
Related: Barbell biceps workout
Barbell curl vs dumbbell curl: The key differences
- You can lift heavier on barbell curls.
- You can supinate your wrists more on dumbbell curls.
- You can gain strength quicker on barbell curls because the weight increments are smaller.
- Dumbbells are better for correcting and preventing muscle imbalances.
- Dumbbells put less strain on your wrists and forearms because you can rotate your palms with them.
Which one is best for muscle growth?
All else being equal, an exercise that can overload a muscle with more resistance will lead to greater hypertrophy than an exercise where you need to use less resistance.
So based on this line of reasoning, the barbell curl is better than the dumbbell curl for building muscle because it lends itself better to lifting heavier weights.
However, the difference in the amount of weight that you can lift typically isn't that significant. And on the flip side of the equation, dumbbells enable you to actively supinate your wrists and thus generate a stronger bicep contraction. By which I mean they let you turn your pinky fingers away from your body to shorten your biceps. 
So in this regard, dumbbells may put more tension through the biceps even though you're lifting slightly less resistance.
Dumbbells also help to correct current and prevent future muscular imbalances. So even if they don't build more mass, which is debatable, they definitely sculpt more symmetrical arms.
Which one is superior for strength development?
The barbell curl is much more effective than the dumbbell curl for gaining strength because you can increase the resistance in more manageable increments.
For example, dumbbells usually ascend in 5lb weight jumps, which is a big leap to make (especially on a regular basis) for a muscle group as small as the biceps.
But with barbells, you can increase the weight in much smaller amounts and thus gain strength more rapidly. You can also use little microplates to make the increments even finer so that you can add weight to the bar more frequently.
In this regard, barbell curls make a better primary, mass-building exercise, whereas dumbbell curls are the superior auxiliary movement for making sure that your biceps grow in proportion to one another.
You can also click the link to learn the difference between a barbell curl and a cable curl and see which is better for building the biceps.
Should you do both exercises?
Since each exercise trains the exact same muscles, it's not necessary to perform both movements. You'd be better off picking either barbell or dumbbell curls and then doing another exercise (like a reverse curl) that still works the arms but which emphasizes different muscles (the brachialis and brachioradialis). This approach will lead to more fun training sessions and better gains overall. 
This way, you won't have overly dominant biceps with weak surrounding arm muscles.
Read More: Straight bar curls vs EZ bar curls
Barbell curls vs dumbbell curls: The verdict
The dumbbell curl is an excellent barbell bicep curl alternative. But is it really the most effective movement of the two?
If you want to build size while limiting muscular imbalances, then yes, dumbbell curls are the better option because they let you make sure that each arm is receiving a similar amount of tension.
However, if you just want to overload your biceps with the heaviest possible weights, then barbell curls are your best bet.
The barbell curl vs dumbbell curl debate has been raging for years and won't stop anytime soon. Although it's virtually impossible to declare a winner (barbells let you lift heavier, but dumbbells offer more control over the target muscles), we hope that our comparison was still useful in helping you select the right exercise for you and your goals.
- Supinator. (2021). Physiopedia. https://www.physio-pedia.com/Supinator
- Baz-Valle, E., Schoenfeld, B. J., Torres-Unda, J., Santos-Concejero, J., & Balsalobre-Fernández, C. (2019). The effects of exercise variation in muscle thickness, maximal strength and motivation in resistance trained men. PLOS ONE, 14(12). https://doi.org/10.1371/journal.pone.0226989