It's easy enough to confirm.
Forks are defined by the outer diameter of the steerer, which is typically either 1"or 1-1/8". The wall is almost always 1/16", so if you have a quill stem you can measure the diameter of the stem which is the same as the inner diameter of the fork. Add 1/8" for the two walls, and you'll have the fork size. ie. a 7/8" stem fits a 1" fork, and a 1" stem (actual, not nominal) fits a 1-1/8" fork.
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