To determine the right size for your crib mattress, measure the interior of your crib, confirm that it conforms with regulation crib mattress sizes, and then check for any gaps once the mattress is in place. Mattresses that are too small for a given crib can pose risks of entrapment or suffocation.Continue Reading
Measure the interior of the crib using a tape measure.
Compare the measurements to standard crib measurements. The measurements should be between 51 3/4 and 53 inches long and between 27 3/8 and 28 5/8 inches wide. If the measurements are different, the crib is not legal, a standard crib mattress doesn't fit it, and the crib should be replaced.
After placing the mattress, stick two fingers between the side of the mattress and the interior wall of the crib. If there is a gap of greater than 1 1/4 inches, the mattress is too small and must be replaced.