These sheets are so soft and comfortable. They also came out of the dryer without wrinkles. They will fit very well on a thick mattress. I have a somma mattress which is basically a mattress with tubes of water inside so it isn't as thick as some mattresses so the sheets were a little big. I just tuck them in and they are just fine. Another nice bonus was that they came with 4 king size pillow cases. I was not expecting such nice sheets at the great price that I got them for.