How to Measure Mattress Defects

A defective mattress is a difficult thing to prove, according to an article in the New York Daily News.

Measuring for mattress defects is a simple task.Measuring for mattress defects is a simple task.
A mattress defect is a sag in the mattress that is deeper than 1-1/2 inches without any weight applied to the mattress. Measuring for this defect can support your claim for obtaining a replacement mattress.

Remove the bedding. Take off comforters, pillows and sheets from the bed. Remove any mattress covers as well.

Inspect the mattress. Look for any areas that are visibly sagging near the edges or in the center. Run your hands over the mattress without applying pressure to feel for large dents in the center.

See how level the mattress is. Ask a helper to stretch a string or tape measure across the mattress area that is sagging. Hold the string or tape measure taut at both ends. If you don't have a helper, use tape to secure the string at both ends. The mattress should be flush with the string or tape measure. A defective mattress will sag below the string or tape measure.

Measure the defect. Measure from the bottom of the sag to the string using a ruler or tape measure. Repeat this process for all areas of the mattress that are sagging.

Write down the measured defects. If the defects exceed 1-1/2 inches, contact the manufacturer to redeem a warranty and ask about replacement.

Things You Will Need

  • Long string
  • Tape measure or ruler


  • The mattress company will send out a technician to validate the measurements and file a warranty claim.
  • Use a bright string when measuring to obtain a clear visual line that does not blend with the mattress's color.


  • Do not apply pressure to the mattress when measuring. This will skew the measurements.