DB/ BB Bench Press Ratio?

Does anyone know of a rule of thumb/ratio to figure out how much you can bench using a barbell vs. dumbbell? For instance, if you can bench 2 dumbells weighing 85lbs each, that would roughly convert to X lbs using a barbell.I would assume that the barbell weight would be greater, but wanted another opinion.

I used to wonder the same thing myself, but really there is no mathematical formula. There is really a big difference in the two – DB’s recruit a lot more muscles for stabilization.

Someone that is used to doing BB’s might be able to bench 300 but only use 65’s with DB’s – whereas someone who’s used to DB’s might be able to do 85’s and only do 240 on the BB.

Just my opinion.