What mattress does a cot bed need?
Short answer: Use a firm, flat, waterproof mattress in good condition, with no raised or cushioned edges, that fits the cot or Moses basket with no gaps. Use the size your frame lists.
- Check the mattress size listed for the frame. 140 x 70cm is common, but not universal.
- Keep every conversion panel, bolt and instruction sheet for the toddler-bed stage.
- Look at adjustable base heights, teething rails and any matching furniture.
What the guidance says
- Use a firm, flat, waterproof mattress in good condition, with no raised or cushioned edges, that fits the cot or Moses basket with no gaps.
- The Lullaby Trust says your baby's head should sink no more than a few millimetres into the mattress.
- Mattresses: look for BS 7177:2008+A1:2011, and BS EN 16890:2017+A1:2021 for cot, travel cot and crib mattresses.
Related questions
What is a cot bed?
A cot with removable sides and ends that converts into a toddler bed, most often taking a 140 x 70cm mattress.
Shop at Baby Kingdom
- Grace Cot Bed, Cot Top Changer + Fibre Mattress - White
- Pembrey Cot Bed and Under Drawer
- Hartley Classic Cot
- Bantam Cot Bed - White
Check each product page for its exact dimensions, mattress size, age and weight limits and safety standards.
More advice
What cot beds does Baby Kingdom sell?Can a 9 month old sleep in their own room?Can a 3 year old have a cot bumper?Guide to cots & cot beds: what to look forMoses baskets buying guide for UK parentsIs a travel cot right for you? Quick quizAll safe sleep and sleep spaces advice →
Sources
- The Lullaby Trust: Baby mattresses and bedding (accessed 2026-10-21)
General information only, not medical advice. Always follow your product's instructions. If you are worried about your baby, contact your GP, health visitor or 111. In an emergency, call 999.