String gauges...

Is there a way to find out what gauge your strings are without any packaging and whatnot? I want to get new strings soon, as the D and G strings in particular are way too light, they don't have a particularly bassy quality about them. I want to make sure I don't get the same gauge strings by accident.

you could get a measuring device
the string guage is in inches
so a 45 guage string would be 0.045 inches in diameter
but usually the strings that come with a bass are 105, 085, 065,045
is suggest that u try out a set of heavy guage strings
but then again the d/g string will always sound a little less bassy then the e/a strings
u could also try to use the e and a string from a standard guage set and the d and g string from a heavy guage set

You're going to have the hardest time trying to find that 1000th of an inch difference in gauges.

Just the next time you pick up your next set of strings, try the heavy guage (50-110), since you probably have standard strings and see how different they are.

that is a good point u got there

Cheers, I think I'll get a heavier set and experiment.

You could take your current set of strings down to any music shop and they should have a calliper that'll measure the gauge.

I'll look into that as well

Should be able to take them down to the shop as fuzzy dice said.
Otherwise if they came with your bass (from the factory/music shop) then try contacting the manufacturer to ask what strings it shipped with