I am an exact size 7 and these run small, so a size 8 fits perfectly.  One benefit that is not advertised is these are non-slip.  When you step in the water, the soles of your feet do not slip and slide on the sandal, which is great if you are in/out of the water often.  I get out on the boat ramp in several feet of water to steady our boat, and won't loose my footing.  The price is significantly less than the high-end sporting good store in San Diego, so worthwhile to order from Amazon.