What depth mattress will your sheets fit? November 22, 2017 00:19 Updated Our sheets will fit mattresses up to 16" deep or thick. Related articles Size Chart / Size Guide Will your fitted sheet stay in place on my mattress? I have queen-sized pillows (20" x 30"), would your standard pillow cases fit? Is your cotton organic? I have a 10" or shallower mattress. Will your sheets stay in place?