Ultra Deep Fitted Sheets

Measure your mattress depth from the top surface to the base, then add the depth of any mattress topper or protector. If the combined measurement is between 39cm and 46cm, an ultra deep fitted sheet is the right choice. If your total depth is 30cm or under, a standard fitted sheet will fit correctly. Between 31cm and 38cm, an extra deep fitted sheet (38cm gusset) is more appropriate. Buying the wrong depth is the most common reason fitted sheets come off during the night.

The difference is the gusset depth. Belledorm extra deep fitted sheets have a 38cm gusset, suitable for mattresses up to approximately 38cm deep. Ultra deep fitted sheets have a 46cm gusset, giving an additional 8cm of fabric to tuck under, making them the right choice for the thickest mattresses or mattresses used with a substantial topper. Buying a deeper sheet than you need will not cause a problem; the excess fabric simply tucks further under the mattress and the elastic holds it in place.

Yes, an ultra deep fitted sheet is specifically designed for mattresses that have a topper. If your mattress is, for example, 30cm deep and your topper adds a further 10cm, your combined depth is 40cm, which falls within the 46cm ultra deep gusset. Belledorm recommends the sheet gusset sits at least 6–8cm deeper than your total mattress and topper measurement to ensure the elastic has enough fabric to grip firmly and stay in place through the night.

A fitted sheet that pulls off overnight is almost always the result of buying the wrong depth for your mattress. If the gusset is shallower than your mattress, there is insufficient fabric to tuck under, and the elastic cannot maintain tension. The fix is straightforward, measure your mattress depth (including any topper), then choose a sheet with a gusset at least 6cm deeper than that measurement. Belledorm's ultra deep 46cm fitted sheets are generously elasticated around all four corners, which provides a more secure hold than corner-tab only designs.

Belledorm ultra deep fitted sheets are available in four fabric options: 200TC polycotton percale, 200TC 100% cotton percale, Egyptian cotton 200TC, and Egyptian cotton 400TC sateen. The polycotton is the most practical for everyday use and easy to care for. The 100% cotton percale has a crisper, cooler feel. Both Egyptian cotton options are made from long-staple fibres for a noticeably smoother surface that softens with each wash, the 400TC sateen in particular has a silky finish suited to those who prefer a softer, closer feel against the skin.

Belledorm ultra deep 46cm fitted sheets are available in single, small double (4ft), double, king size, and super king. If you have a non-standard bed, such as an IKEA Euro King, emperor, or custom-size mattress, the extra deep 38cm range carries a wider size selection, including special sizes. Check the individual product listing for precise measurements before ordering, and measure your mattress rather than relying on the bed frame label, as mattress dimensions can vary between manufacturers.

The right choice depends on how you sleep. The 200TC cotton percale has a clean, crisp feel and is highly breathable, a good choice for warm sleepers or those who prefer a fresh, hotel-style finish. The Egyptian cotton 400TC sateen has a smoother, slightly silkier surface due to the sateen weave and the longer-staple Egyptian cotton fibre, which reduces friction against skin. Both are pre-shrunk and designed to hold their shape and depth through repeated washing. If you sleep warm, percale; if you prefer a softer, more settled feel, the Egyptian cotton sateen is worth the step up.