Reading your crib before you order

Look at the short ends first

Stand at the foot of the crib and look at the two short sides. If you can see through them, it is a slatted end, and the panel has to wrap the last slat at each corner to stay put. If they are boards you cannot see through, it is a solid end, and the panel needs a different cut, because there is no end slat to wrap and no gap to pass a tie through.

This one answer rules out more of the catalog than anything else you could measure, which is why will it fit my crib asks it before it asks anything else.

Full size or mini

A mini crib is not a small full size crib. The perimeter is shorter by enough that a full length panel gathers and sags on it, and a sagging panel is the one condition under which a panel should not be in the crib at all. 2 pieces here are cut for mini frames.

Count the corners the ties have to reach

Ties fasten on the outside of the frame, so whatever they pass through has to have an outside. Drawers, a solid base panel or a crib pushed flat against a wall all take away the room a hand needs to pull a tie snug. Check you can get behind all four corners before the panel arrives, not after.

Then check the age, not the crib

Take the panel out of the crib once your baby can pull up to standing against the crib side, which starts at around six months. An older baby can use it to climb.

If your baby is close to that already, the honest answer is that a panel is the wrong purchase now, however well it would have fitted the frame.