Round Fitted Sheet: Sizes, Fit, and How to Measure a Circular Bed

A round mattress has no corners for an elastic hem to grip, which is exactly why a rectangular fitted sheet stretched over a circular bed almost always ends up wrinkled, gaping, or sliding loose. A proper round fitted sheet is cut in the round to begin with. Here's how sizing works for a circular bed, what diameters exist, and how to get a fit that actually looks intentional.

Why a rectangular sheet never really works on a round bed

Rectangular fitted sheets rely on elastic pulling in at four corners to grip a mattress. A round mattress doesn't have corners, so there's nothing for that elastic to catch onto, no matter how hard the fabric stretches. The result is usually loose folds of extra fabric bunched at odd points around the circumference, and a sheet that shifts every time someone gets in or out of bed. A round fitted sheet solves this at the pattern level, the fabric is cut as a circle to begin with, so the elastic hem runs continuously around the true edge of the mattress instead of trying to approximate one.

How round mattress sizing works

Round beds are sized by a single measurement, diameter, rather than the length and width used for rectangular mattresses. SGI's round fitted sheets come in three diameters:

To measure your own mattress, run a tape measure straight across the widest point, through the center, rather than around the outside edge, that outer measurement is the circumference, not the diameter you need. If your mattress falls between two sizes, sizing up gives the pocket more room to work with than sizing down.

Round mattresses are less standardized across manufacturers than rectangular ones, since there's no single industry convention the way there is for Twin, Full, or Queen. Two round beds both marketed as "80 inch" can differ by an inch or two in practice, which is part of why measuring your actual mattress before ordering matters more here than it does for a standard rectangular bed.

Deep pocket and 360 elastic matter even more here

On a rectangular bed, elastic only at the corners can sometimes get away with holding a sheet in place. On a round mattress, there are no corners to rely on at all, so the elastic has to do the entire job by itself, evenly, around the whole circle. SGI's round fitted sheets use 360-degree all-around elastic paired with a genuine deep pocket, which is what lets the sheet hug the true curve of the mattress instead of pulling tight in a few spots and loose everywhere else.

Our Pick

600 Thread Count Round Fitted Sheet

• Cut as a true circle, not a rectangle
• Deep pocket + 360-degree all-around elastic
• 3-piece: fitted sheet + 2 envelope pillowcases
• 76", 80", 84" diameters, 100% Fit Guarantee

From $49.99

Shop round fitted sheets

Want the plusher weave? The 1000 Thread Count round fitted sheet starts from $64.99, in the same 76", 80", and 84" diameters.

Fabric and colors

Both versions are woven from long-staple cotton, breathable and smooth, in 9 colors: White, Light Grey, Dark Grey, Butter, Burgundy, Moss, Navy Blue, Taupe, and Black. The 1000 Thread Count sheet steps up to a denser, more lustrous weave for a plusher hand, while the 600 Thread Count version gives the same everyday hotel-quality feel at a lower price point.

Round mattresses tend to be statement pieces in a room, often the visual center of a space designed around them, so the sheet underneath still matters even though most of it disappears beneath a duvet or comforter. A crisp, well-fitted sheet in a color that complements the rest of the room keeps the whole setup looking intentional rather than like a rectangular sheet forced into service.

If you need the whole set, not just the fitted sheet

This guide focuses on the fitted sheet specifically, since that's the piece where a round mattress causes the most trouble. If you're outfitting the bed from scratch and want the flat sheet and pillowcases in the same round cut, our round bed sheets guide covers the complete set.

Care instructions

Machine wash in cool or warm water and tumble dry on low. The cotton is fade-resistant and holds its softness wash after wash, the round cut doesn't change how the fabric behaves in the laundry, only how it's shaped. A round mattress sheet also goes through the wash the same way any fitted sheet does, so there's no special folding or handling required beyond the usual care that keeps cotton soft over time.

A few common questions

Can I use a regular fitted sheet on a round mattress?

Not well. Without corners for the elastic to grip, a rectangular sheet bunches unevenly and works loose quickly. A sheet cut as a true circle is the only reliable way to get a snug fit on a round bed.

How do I measure my round mattress?

Measure straight across the widest point, through the center, to get the diameter. Don't measure around the outer edge, that gives you circumference, which is a different number entirely.

What's the difference between the 600TC and 1000TC round fitted sheet?

Both use the same deep pocket and 360-degree elastic construction. The 1000TC version has a denser, more lustrous weave for a plusher feel, while 600TC offers the same hotel-quality cotton at a more accessible price.

Does the round fitted sheet come with pillowcases?

Yes, both versions ship as a 3-piece set: the fitted sheet plus 2 pillowcases with envelope closures.