The size is 16x12x4 I used a 2" wide webbing for the strap as I felt that would be more comfortable with a narrow strap.
I also put a zipper in the top of the bag, to keep contents from falling out
Sorry for the wiggle, it is late at night.
and here is a look at the interior. I put a pocket on the back side of the bag too. I used a taffeta type material, so that things will not "grab" the the lining when you take them out and put them in.
the basic pattern for the bag can be found here and the idea for the zipper in the top came from here
on a weather note, we got a severe winter storm again today. wind from the northeast this time and more snow. the forecast is for 6+"