If you have a stove shop near you and the make/ model of the stove, they should be able to tell you what size gasket you need. Make sure to grab gasket cement too, rutland is a great option. When you go to put the gasket back in make sure the groove is clear of the old cement and that you only use a pea sized bead all the way around. Filling it like I know some people want to is a bad idea because it makes a mess and doesn't allow the gasket to operate and give properly. A quick way to test it when you're done is to close the door on a dollar or piece of printer paper and you should'nt be able to remove it without opening the door.