Here is a growth chart. It's kinda confusing to read.
http://home.comcast.net/~kkingpdx/puppygrowthchart.html
Take your pups age in weeks, his weight and then go to the bottom of the chart to find his final approximate weight.According to the chart, your pup will be over 6 lbs.
I stink at explaining - hope someone else can give you better instructions.