Some manufacturers think the full beds and queen size mattresses are the same (they aren’t), so they say their comforters are compatible with both bed sizes (they’re not). If your comforter is labeled full/queen, it is more likely to be too big for a full and too small for a queen, so pay extra attention to the dimensions whenever you run across a comforter with this label. If you want a comforter that ideally fits your mattress, it may be best to avoid comforters marked suitable for both sizes.