UK Cot & Cot Bed Mattress Sizes: Standard Dimensions & Gap Limits

Two sizes cover almost every cot sold in Britain: 120cm by 60cm for a standard cot and 140cm by 70cm for a cot bed. Furniture in Fashion's 2026 dimensional report sets out those measurements alongside the requirement that matters more than either, which is fit. British Standard BS EN 716 governs cots and folding cots for domestic use, and the Lullaby Trust advises a firm, flat mattress fitted snugly with no gaps a baby could roll into, which is why the mattress must always be bought to the cot rather than assumed from a category name. The report explains how to check the gap in seconds, why imported and second hand frames need measuring internally, and how a cot bed converts without ever becoming compatible with a 190cm by 90cm UK single. It also covers positioning, access clearance and changing surface heights in the small third bedrooms most British nurseries occupy....