Cleaning stove grates with ammonia: I used 1/4 cup of ammonia per grate. So 1/4 times 4. If your grate will fit in a ziplock baggie, that is even better. Mine were too large so I put all four of them in a big garbage bag along with my ammonia. Tied it up, and let it sit over night in the laundry room. Also, recommended to put bag outdoors on a warm sunny day.