M&S Stay Cool 10cm Depth Mattress Topper im Test

The M&S Stay Cool 10cm Depth Mattress Topper is a polyester fibre topper filled to 10cm, the deepest fill Marks & Spencer states for any of its own toppers. It is built to soften a mattress that feels too firm, not just to add a thin layer of padding, and four elasticated corner straps hold it on the bed.

Construction and care

M&S says its Stay Cool technology gently regulates body temperature by balancing heat and airflow. The product page gives no measurement or test behind that, so our temperature score rests on what can be checked: polyester fill under a polyester cover, comfortable in most bedrooms but not a cooling material in itself.

The care label is the drawback. This topper cannot be washed, tumble dried or dry cleaned, so it needs a washable mattress protector over it from the first night. A fibre fill this deep also packs down where you lie, so give it a shake and turn it every few weeks to keep the loft even. Buyers rate it highly: 21 reviews on the M&S site average 4.8 out of 5.

Sizes and prices

Prices from the M&S product page at the time of writing (October 2026). M&S lists its sizes in feet, and the centimetre sizes above are the UK standard for those beds; there is no small double or emperor. M&S states no sleep trial or guarantee, and its returns policy accepts mattress protectors, the category M&S sells its toppers in, only unopened with the hygiene seal intact.