1/8 oz. to 3/8 oz. are the most common size used for walleye. This of course will depend on body of water circumstances and fishing environment. Some anglers choose to run lighter jigs when walleye are finicky, this allows the angler sensitivity to feel the walleye sucking in the jig.
3/8 oz to 5/8 oz jigs are very popular for larger bodies of water that can become rough on the surface or for river fishing where there is a fast moving currents.