Baby mattress sizes explained
Short answer: Common UK sizes include 120 x 60cm (cot), 140 x 70cm (cot bed and many toddler beds) and 100 x 50cm (space-saver). Cribs, Moses baskets and travel cots need their own fitted mattress.
Step by step
- Measure the inside of the frame.
- Make sure there are no gaps around the edges.
- Buy a new mattress where possible.
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.
Shop at Baby Kingdom
- Tutti Bambini Pocket Sprung Cot Bed Mattress (70 x 140 cm)
- Ickle Bubba Fibre Cot Bed Mattress 140 x 70cm
- Obaby Foam Cot Mattress 120 x 60 cm
- Obaby 100 x 50cm Foam Cot Mattress with Washable Cover
Check each product page for its exact dimensions, mattress size, age and weight limits and safety standards.
More advice
Can a newborn sleep on a raised or tilted mattress for reflux?Cot mattresses buying guide for UK parentsWhat cot bed mattresses does Baby Kingdom sell?How do I check a cot mattress fits?When should I buy a Moses basket mattress?Can an 11 month old sleep on a raised or tilted mattress for reflux?All cot and baby mattresses 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.