To measure a mattress for sagging, you can follow these steps:
  1. Remove bedding: Take off all bedding, including sheets, pads, and toppers. 
  • Smooth the mattress: Remove any wrinkles from the top of the mattress. 

    Find the sag: Look for any visible indentations or unevenness. 

  • Measure the sag:
  • Lay a straight edge, like a yardstick or level, across the mattress. 
  • Place the tip of a measuring device at the deepest point of the sag. 
  • Measure from the bottom of the measuring device up to the lowest point of the dip. 
  • Record the measurement: Note the measurement in inches. 
  • Take a photo: Take a picture with the measuring device visibly showing the depth of the sag.