While I haven't yet used these, as soon as I opened the package the first thing noted was the weight of the "canvas": more like coarse/utility weight muslin than canvas.
  Washed on cold & air dried: shrinkage improves the density of the cloth a bit (not much), but they SHRUNK BY MORE THAN A THIRD!!'
  At this point I can't imagine using these to carry more than 2 lb- NOT suitable for groceries, books etc. Lightweight gifts or lunches, IMO