roddent weight

I've been looking to start ordering my rodents online since it will save me a boat load of cash. Every site i go on it just says the size of the rats (pup, weaned, small ect.) so I was just wondering if you guys have a general weight/size idea.
Thanks

I order from Rodent Pro, they have the weights and length listed for each of the sizes. Mine have generally weighed right in the middle of the range they give with a few higher and a few lower.