I found some fairly comfortable mattresses for my fold down bunks from Ikea, the dimensions are 27 1/2 x 63 inches perfect width, but the length is short of what could be there, but i figure it is extra storage on the end and if my kids are too tall for the matress they will exceed the weight rating for the bunks.
VYSSA SLUMMER Mattress for small bed - IKEA
VYSSA SLUMMER Mattress for small bed - IKEA
