How to Measure Deep Pocket Sheets | Get The Right Fit

For the full breakdown, see our best Extra Deep Pocket King Sheets guide.

The right way to shop for deep pocket sheets starts with a tape measure, not a guess about your mattress. Measure the mattress depth from the bottom edge where it sits on the frame to the highest point of the sleeping surface, include any mattress pad or topper that stays on the bed, and then look for a fitted sheet with a pocket depth a few inches greater than that number. A little extra depth is what lets the elastic wrap under the corners and hold all night.

Measuring Your Mattress the Right Way

Strip the bed completely. Remove all linens, blankets, and any topper you do not plan to keep using permanently. Cuddledown’s guide says to leave on any mattress pad or topper you will continue using, because those add real height the sheet must cover.

Run the tape measure from the bottom seam of the mattress down where it meets the foundation or frame up to the highest point of the sleeping surface. Do not press down or compress the mattress while measuring — one guide specifically warns against this, since compression gives you a false reading that leads to a shallow sheet.

Measure in several places. Mattresses can crown in the center or sit unevenly on a frame, so take readings along both sides and in the middle. Use the deepest measurement you find, not the average.

Pocket Depth Ranges and What They Mean

Retailers group pocket depths into standard categories, though ranges vary somewhat by brand. A common breakdown is roughly 10–12 inches for standard pockets, 14–16 inches for deep pockets, and 17–22 inches or more for extra deep. Another sizing guide lists deep pocket as fitting mattresses 15–17 inches thick, while a separate commercial guide puts the deep-pocket range at 15–22 inches.

What matters is not the label but the number. Check the product listing for the actual pocket depth, sometimes called pocket size, fitted depth, or corner depth. Casper’s bedding guide frames it as matching the sheet to the mattress height rather than chasing a category name.

How Much Allowance Should You Add?

Add a few inches of breathing room to your measured mattress depth. One major retailer recommends pocket depth 1–3 inches longer than the mattress depth, cautioning that a sheet labeled “deep” may still run short if the mattress sits at the top of that range. A separate bedding guide suggests 2–4 inches of extra allowance, and another recommends at least 4 centimeters of additional depth for tucking under the mattress.

The trade-off runs both directions. A pocket too shallow lets the corners pop off and the sheet work loose overnight. A pocket much deeper than needed can fit loosely, though strong elastic sometimes compensates. Aim for a couple inches of slack — enough to tuck under, not so much that the sheet pools.

If you sleep with a topper, its thickness counts. Several guides state this directly: add the topper’s height to the mattress measurement before comparing pocket depths. Shopping for extra deep pocket king sheets is easier when you already know your exact number.

Common Mistakes That Ruin the Fit

• Measuring only the fabric. Measure the full sleeping surface height, not just the side panel.
• Ignoring the crown. Pillow-top and Euro-top mattresses bulge in the middle, so center readings matter.
• Forgetting the topper. Any pad or protector that stays on the bed adds height.
• Measuring one side only. Uneven frames and sagging make one reading unreliable.
• Buying equal depth. A pocket the same size as the mattress depth has no room to tuck under.

Once you have your deepest measurement plus allowance, you can shop with confidence. Check that the listing’s pocket depth covers your number, and skip the guesswork entirely.