From the proportions of the photo, those look to be 1 or 1 1/2" handles. Usually if you make handles from fabric, you wind up trippleing the fabric, so a 3" width of fabric would make a handle about 1" wide. If you want to go with webbing, I would go with 1". I have made dozens of bags and use 1". I have used nylon, polypropelene & cotton. They all seem to be about the same strength.