What Size Is a Baby Crib Sheet? | The 28×52 Standard

A standard baby crib sheet measures 28 inches wide by 52 inches long, sized to fit a full-size crib mattress.

Most parents discover the answer to what size is a baby crib sheet only after buying one that doesn’t fit. The mattress beneath matters more than the sheet itself — a sheet built for the U.S. standard crib mattress will fit most full-size cribs sold today. Here’s the measurement breakdown and what to check before you buy.

Why 28 x 52 Inches Is the Standard

A standard crib sheet is 28 x 52 inches because that’s the size of the full-size crib mattress underneath it. The Consumer Product Safety Commission defines a full-size crib mattress as at least 27 1/4 inches wide by 51 5/8 inches long, and no more than 6 inches thick.

Crib frames themselves are held to a similar standard. The CPSC specifies full-size crib dimensions of 52 3/8 inches (plus or minus 5/8 inch) by 28 inches (plus or minus 5/8 inch), which is why sheets and mattresses pair so consistently across brands.

Some manufacturers list a height dimension too, and a sheet described as 28 x 9 x 52 inches simply accounts for the mattress depth. The pocket depth matters for thick mattresses, but the flat width and length remain the same.

Which Mattresses Take a Standard Sheet — and Which Don’t

A standard 28 x 52 inch fitted sheet works on full-size crib mattresses, and often on toddler mattresses as well, since many toddler beds reuse the same mattress dimensions. The sheet may run slightly loose on a thinner toddler mattress, so check the fit after you put it on.

Mini cribs, bassinets, and play yards use different dimensions entirely. Mini crib sheets commonly measure about 24 x 38 inches, while bassinet sheets vary by model — the BabyBjörn fitted crib sheet, for example, is 41 x 21 inches. These smaller sheets are not interchangeable with the standard size. If your sleep space is anything other than a full-size crib, measure the mattress and buy the model-specific sheet.

Fit and Safety Rules Worth Checking

A crib sheet is only safe when it fits tightly. Loose fabric can bunch under a sleeping baby, so the sheet should sit smooth with no sagging or slack across the surface. Always use a fitted sheet in the sleep space — never an adult-size flat sheet, which can shift and create a hazard.

The mattress itself should also fit snugly inside the crib frame. Consumer Reports advises leaving no more than a half-inch gap between the mattress and the crib sides.

Before you buy, measure your mattress: length end to end, width across, and thickness. Then check the sheet’s elastic after washing, since shrinkage over time can loosen the fit. Tug the corners after you put it on — the sheet shouldn’t ride up easily. Expect to pay roughly $10 for a basic sheet up to about $40 for a designer option, per Consumer Reports.

If the fit still isn’t right on a standard crib, the sheet may be the culprit — not the mattress. But for most standard cribs, a 28 x 52 inch fitted sheet is the safe, correct choice. If you’re shopping for a baby girl, our roundup of top-rated baby girl crib sheets can help narrow down safe, snug options.

FAQs

Do crib sheets shrink after washing?

Cotton crib sheets can shrink slightly in the dryer, which can affect how tightly they fit over the mattress. Wash in cool or warm water and dry on low or line-dry to minimize shrinkage. If the sheet becomes loose after repeated washes, replace it rather than layering anything underneath to take up slack.

Can I use a standard crib sheet on a toddler bed?

Often yes, because many toddler mattresses are the same 28 x 52 inch size as standard crib mattresses. If the toddler mattress is thinner than 6 inches, the sheet may fit more loosely, so check the corners after installing it. Some toddler beds, however, use different mattress sizes, so measuring first is always the safest move.

What’s the difference between a crib sheet and a bassinet sheet?

Crib sheets are sized for a 28 x 52 inch full-size mattress, while bassinet sheets are made to fit much smaller, oval or round bassinet mattresses that vary by model. A standard crib sheet will be far too large for a bassinet and could bunch dangerously. Buy bassinet sheets that match your specific bassinet model.