Standard size mattress for crib / toddler bed (51.75 x 27.75 x 5.75 inches).
My kids have outgrown, we no longer need it. At least 4 kids have used this mattress in their crib. Because babies are so light, the mattress is just as firm as when it was brand new. However the outer vinyl layer is torn in several places. Other than the vinyl, mattress is like new, but the vinyl is substantially torn.
If I had another baby, I would spend $20 on a zip up mattress cover (like this one: https://www.target.com/p/sealy-safetycase-protective-crib-38-toddler-zippered-mattress-encasement/-/A-17393901 ) and it would be literally good as new.
Mattress is double sized. One side is firmer, for babies/cribs. One side is a little softer, for toddlers/tot beds.
No bedbugs or other pests, nonsmoking home. We do have a dog but she has never been in the crib.