How big would you expect this dog to be? (beagle lab mix?)?

Me and my family were looking at dogs and we saw this very cute beagle lab mix (I don't know if it's anything else, that's all the shelter said) It was 5 months old and it was probably a little taller than a beagle but it's body was a thinner than a beagles. Right now it was a pretty good size but like I said, only 5 months old, should it get a lot bigger? About how big (on average, I know it's hard to tell on mutts) should it get? Is there anyway to tell if it will still grow alot?