confused about measuring proper block height

Information provided on IBT website indicates blocks approximately 7" in height are needed to achieve a 5 degree incline for a 80" long bed. I am somewhat confused because with 5 & 1/4" blocks I have achieved a 6" increase in height at head of bed and smartphone incinometer app indicates a nearly dead-on 5 degree angle.Doesn't seem possible that both scenarios could be correct. Any clarification appreciated.

Hi, it depends where your bed legs are located on the frame. The guide is assuming you measure from the top of the bed frame to the floor at both ends of the bed.