Crib Mattress Size?




Being aware of the standard crib mattress size is important when shopping for your baby’s mattress. I still remember measuring over and over again, when I was shopping for Samantha’s crib mattress.


Now looking back at it, I am glad that I made those extra measurements. Because not all the mattresses were standard size.


Standard Size Crib Mattress

Most crib mattresses. on the market are standard size and will fit standard size cribs. However, some may vary slightly in length and width and may be a potential safety hazard, if not fitted with the proper crib. So please take these measurements very seriously.

The crib mattress that you choose for your baby should have the proper dimensions:

    Baby Crib Mattress Size
  • 51-5/8 inches in length and 27-1/4 inches wide

The depth of your crib mattress should:

  • Never be greater than 6"
  • Can range between 4 and 6 inches for foam mattresses
  • Can range between 5 and 6 inches for coil mattresses

Click the link for tips on the best way to measure your baby mattress size accurately.

Thickness does not affect the safety of the mattress, but make sure you are using the correct sized crib sheet. The crib sheet should fit tightly over the corners of the mattress and tuck securely underneath it.



It is very important that the mattress fits snugly against each side of the crib. A mattress that doesn’t fit properly might allow your infant to crawl beneath it.

I read that the Consumer Product Safety Commission issued these specifications to prevent suffocation and entrapment of a baby’s head between the sides of the crib and the mattress.


You must be aware of these consequences in order to keep your little one safe. click the following link for information on crib size. If the measurements that you take are slightly different, make sure it passes the “finger test” described below. Sometimes mistakes occur at the manufacturing side and crib mattresses are produced that do not follow the standard crib mattress size regulations.

Last June, 20,000 were recalled details.


Test the fit using the "Finger Test":

Try fitting two side-by-side fingers between the mattress and the side of the crib or rails. If you are able to do this, than the crib mattress is too small. You should not be able to fit more than one finger.

Crib Mattress Sizecrib mattress


Non-Standard Size Crib and Mattress

If you decide to purchase a non-standard size crib, you should get a hold of the manufacturer and get a crib mattress specifically designed for your crib. Also, for your baby’s safety and comfort, make sure the mattress is of high quality and meets the recommendations listed throughout this site.


Summary of recommended actions:

  • Perform the "finger test" to determine if the mattress is a good fit for your baby’s crib.
  • Make sure the assembly instructions that came with the crib and the mattress indicate the standard measurements of 51-5/8 inches long, 27-1/4 inches wide, and no more than 6 inches deep.
  • Double check by measuring the crib mattresscrib mattress and crib yourself.




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