We purchased the crib used but wanted a new mattress for safety reasons. The crib company says the crib is suitable for any standard sized mattress under 6”. The mattress I purchase is 27.5 x 52 x 5.5. There’s not so much of a gap on the sides but about a .5 inch gap on the top and bottom as well as enough room to reach my hand down the corners.

Maybe there’s small spaces are normal but I could really use some reassurance. I ordered the mattress through amazon and could potentially still return it but because it “expands” after opening it won’t fit in the box it came in.

This is with a mattress protector and sheets already placed on the mattress:

The gap with the mattress pushed to one side: