Quilt sizes.

Hi everyone. I'm only relatively new to quilting (I have 4 sons so I learned by making a quilt for each of them. I figured that by the time I finished the fourth I'd know what I was doing before I did one for me!!!)
Quick question.
I have a friend who is expecting a baby. My teenagers no longer sleep in cots/cribs so I can't quickly measure their beds, so how big should I make a quilt for the baby?
Thanks in anticipation...

I always make my baby quilts around 40" x 40"  Sometimes they are a little more rectangular (40 x 45 or 36 x 40, you get the idea), depending on the pattern.  I just happen to have a store-bought crib quilt here I am quilting for a friend.  It is 42.5" x 34". 

Hope that helps!

You might consider planning this so that the back of the quilt is not wider than a fabric width (typically 44/45"), that way you can use one solid piece of yardage for the back.  Unless you want to piece the back as well, but I found this a really nice point to consider on my first quilting projects.  After getting the front together I was anxious to get to the quilting part and was happy to just cut a length of yardage and be ready to go!  I noticed the recommended sizes for crib quilts are coming in under that measure, but just in case you were thinking of just an inch or two bigger, you might want to rethink it if you don't want to piece the back!

Thanks so much.
By the way, that's a good idea about the backing. I never would have thought of that!
It's been a cold rainy day in Melbourne, Australia, so I used the time to finish my son's quilt. 4 Boys... 4 quilts. Phew!
Now on to the baby quilt!!!