---
title: "Memory Foam"
description: "What memory foam is, why it moulds slowly and changes with temperature, and how density describes its grade."
url: "https://bedguide.co.uk/glossary/memory-foam/"
category: "glossary"
primary_entity: "memory foam"
date_published: 2026-10-21
date_modified: 2026-10-21
---

# Memory Foam

> Memory foam is a type of polyurethane foam that slowly springs back after you press it. It also changes with temperature. Body warmth softens the area you lie on, and a cooler room makes it feel firmer. Foam density in kg/m³ and hardness describe the grade better than the thickness in a product name.

**Definition.** Memory foam is a polyurethane foam that slowly springs back after pressure. Body warmth softens it, and a cool room makes it firmer.

Also called: visco-elastic foam, viscoelastic foam, memory foam layer.

Most mattresses use memory foam as one comfort layer over firmer foam or
springs. Very few are memory foam all the way through.

New memory foam can smell for a few days after unpacking. Air the room well.

Full guide: [memory foam mattress explained](/mattresses/memory-foam). Also:
[foam density explained](/mattresses/foam-density-explained).

---

Source: https://bedguide.co.uk/glossary/memory-foam/ · BedGuide — independent UK bed guide; paid links are labelled (see /how-we-make-money/). Facts checked against official sources where possible; see https://bedguide.co.uk/editorial-policy. Report an error: https://bedguide.co.uk/corrections.