What mattress does a cot 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 internal size and buy a mattress that fits with no gaps.
- Adjustable base heights let you lower the mattress as your baby learns to sit and stand.
- Teething rails protect the top rails from little teeth.
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?
A framed baby bed with fixed sides, usually taking a 120 x 60cm mattress.
Shop at Baby Kingdom
- Obaby Stamford Space Saver Cot in Warm Grey
- Coleby Space Saver Cot
- Stamford Space Saver Sleigh Cot - White
- Hartley Classic Cot
Check each product page for its exact dimensions, mattress size, age and weight limits and safety standards.
More advice
Can a 6 month old sleep in a cot?Can a 5 month old sleep in a cot?Can an 11 month old have a cot bumper?Cots buying guide for UK parentsFlat head and tummy time quizBaby product standards 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.