Dumbbell vs. barbell weights

[bekkilyn]

If you have two 20 lb dumbbells, is it considered to be the same weight as one 40 lb barbell? If not, how do these weights compare?

[LisaS]

Most people cannot take their BB weight on upper body lifts and use half that on DB and be successfull for the same number of reps. The weight is surely half (or double) but the unilateral movements are harder to do.

Example: If I can bench press 70 lbs for 6 reps using BB, logic would indicate I should be able to do the same with 35 lbs dbs but I cannot. The stabilizers get much more involved with the DB movement and lighter weights are needed to accomplish the same number of reps. Perhaps 30s or even 25s/27.5s.

[bekkilyn]

Thank you, that's really good to know.

[LisaS]

Found this rule of thumb on Mike Boyle's site:

We also use the following formula for any dumbbell variations.
DB weight = 80% of bar weight / 2

so 100 lb BP would be equivalent to using 40 lb DBs

[TheWookie]

Now that's a useful nugget. Thank you Lisa!

[bekkilyn]

Yes, thank you! That is wonderful!

[chinadoll]

Thanks! I had noticed that my BB weight was higher but this thread explained it nicely and gives the formula to figure out appropriate weights in the future if I don't have BB access.

[JennyR]

I am in Stage 1 working out at home. I don't have a BB so have been wondering the same thing. Thanks for the info.

[kratai856]

Really good to know. Thank you.

[pintobean]

Thank you. I work out from home as well and don't have access to BB at the moment.

[WildStrawberry]

So, is the barbell really "unnecessary"? I always assumed that there was a point to doing some exercises with a bar and some with two separate dumbbells.

[missjane]

Eventually, you will outgrow dumbbells for squats and you really can't do a proper conventional deadlift with dumbbells.

[WildStrawberry]

Ok, thanks missjane