Cot mattress vs cot bed mattress: which is better?
Short answer: They do different jobs. A cot mattress is a firm, flat mattress for a standard cot, usually 120 x 60cm. A cot bed mattress is a firm, flat mattress for a cot bed, usually 140 x 70cm, which carries on into the toddler-bed stage. Choose by your baby's stage, your space and how long you want to use it.
Cot mattress
Used from birth for as long as your child sleeps in the cot.
- Measure the inside of the cot. The mattress should fit with no gaps.
- Choose firm, flat and waterproof. Your baby's head should sink no more than a few millimetres.
- Check for a fire-resistant label and the relevant British Standard.
Cot bed mattress
Used from birth through the cot and toddler-bed years.
- Confirm the cot bed's mattress size before buying, as frames vary.
- Firm, flat, waterproof, with a snug fit.
- Choose foam, spring or fibre for your budget and how much you need to wipe or wash it.
| Cot mattress | Cot bed mattress | |
|---|---|---|
| Typical use | from birth for as long as your child sleeps in the cot | from birth through the cot and toddler-bed years |
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
How long can you use a cot mattress?
From birth for as long as your child sleeps in the cot.
How long can you use a cot bed mattress?
From birth through the cot and toddler-bed years.
Shop at Baby Kingdom
Browse cot mattresses 120 x 60
- Obaby Pocket Sprung Mattress - 120 x 60cm
- Tutti Bambini Sprung Cot/Cot Bed Mattress
- Obaby Sprung Mattress - 120 x 60cm
- Obaby Moisture Management Mattress -120x60cm
Check each product page for its exact dimensions, mattress size, age and weight limits and safety standards.
More advice
What space saver cot mattresses 100 x 50 does Baby Kingdom sell?Can I buy a second-hand cot mattress?Travel cot mattress vs cot mattress: which is better?What cot mattresses does Baby Kingdom sell?Guide to mattress protectors: what to look forCrib and Moses basket mattresses buying guide for UK parentsAll 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.