How Long Should a Cot Bed Mattress Last?
Published 12 Jan 2026
A cot bed mattress should last at least 5 years (that's about 20,000 hours) - that's what a cot bed is designed to do.
The life of the mattress depends on it not dipping or denting and giving good support, which is important for the safety and development of your child.
The durability and support will depend on the construction and the quality of components used.
Remember: your cot bed mattress will also be used as a trampoline, as well as you sitting on it to do the night-time bed stories!
The Pocket Spring Challenge
Consider this: the springs are 6cm deep, and a cot mattress should not be deeper than 10cm (British Safety Standard). That's 2cm of foam top and bottom. (2 + 6 + 2 = 10cm)
OK, so your baby/toddler is lying on 2cm of foam supported by springs from below. It's the foam that takes the initial weight of your baby/toddler; it's the foam layer that ensures the support and comfort.
Why Foam Quality Matters
Foam as a product does not like "Heat, Weight, and Damp" - it breaks down when subjected to these three effects. Well, that's a shame, because that's exactly what a baby is: hot, wet, and damp!
Heat, weight, and damp break down the foam, weaken it, and make it dip or dent. The quality of foam is absolutely key. The better the quality, the longer your mattress will give good comfort, support, and durability.
For a cot bed mattress to last 5 years, the foam quality should be 33 CMHR or up to 50 CMHR.
90% of cot mattresses sold in the UK use foam of 28 CMHR or less to meet a price point! It's highly unlikely this quality of foam will give your baby 5 years of comfort and support. In fact, you may find it dipping after a few months. Please read some of the feedback on Amazon for these cheap mattresses!
Natural Alternatives
Most natural mattresses made of coir will last longer. Quality coir is inherently stronger and firmer than basic 28 CMHR foam, and it's dearer. The solid block of coir is very firm (what's prescribed by the Lullaby Trust). The lambswool above the coir offers a welcoming layer.
For an even more durable, comfortable natural mattress, pocket springs can be encapsulated in coir with lambswool above the coir layer. This really does tick all the boxes, and you're moving away from foam toward a sustainable, natural product.
What About Fibre?
Fibre is an interesting component made from recycled plastic bottles. Fibre is highly breathable, cooler than foam, and doesn't have a petroleum smell like foam may have if not aired correctly. Fibre doesn't need ventilation when new. It's also cheap as chips!
However, fibre gives very poor support and will show signs of denting after a few months. Fibre may suffice for a mattress used occasionally at the grandparents' for a few visits a year, but there's not a cat in hell's chance that a fibre mattress will give good support and comfort in a cot bed for 5 years - that's 22,000 hours!