The usual answer is every 7 to 10 years. For a child's mattress, that's wrong.
Almost every guide you'll find on this is written about adult mattresses, where the limiting factor is the foam or the springs wearing out. Children's mattresses rarely reach that point. They get outgrown, or they get ruined, long before they wear out.
For a child, plan on every 5 to 7 years, and expect at least one replacement driven by size rather than age.
Why children's mattresses are different
They get outgrown. A cot bed mattress is 140cm long. A shorty is 175cm. A standard single is 190cm. Most children move through at least two of those, and the trigger is height, not wear.
They take more punishment. Accidents, spilled drinks, illness, and a decade of a child treating the bed as a trampoline. Even with a protector, a child's mattress absorbs far more than an adult's.
Growing bodies need support. A mattress that's gone soft in the middle isn't just uncomfortable, it stops supporting a spine that's still developing.
They get handed down. Perfectly sensible with a frame. Less so with a mattress, especially one that's already done six or seven years with an older sibling.
Signs it needs replacing
Check the mattress properly rather than going by the date. Strip the bed, look at it in daylight, and press down across the surface.
- A dip or body impression that doesn't spring back within a minute or two
- Lumps, or springs you can feel through the surface
- Staining or a smell that survives a proper clean
- Your child says it's uncomfortable. Children rarely complain about a bed unless something's genuinely wrong with it
- Waking with aches, or waking repeatedly with no other explanation
- Allergy symptoms getting worse at night or on waking
- Edges collapsing, so sitting on the side feels like it's giving way
Any two of those together and it's time, whatever age the mattress is.
Size changes: the ones most people plan badly
These catch families out because they arrive faster than expected.
| Stage | Typical age | Mattress size |
|---|---|---|
| Cot bed | Up to 4 or 5 | 70 x 140cm |
| Shorty single | 4 to 8 | 75 x 175cm |
| Standard single | 6 upwards | 90 x 190cm |
| Continental single | Teens | 90 x 200cm |
A rough rule: if your child's feet are within 10cm of the end, they've got about a year left in it.
The step most people skip is the shorty. It's genuinely useful in a small room and it buys three or four years, but it does mean an extra mattress along the way. If space allows, going straight from a cot bed to a standard single is one fewer purchase.
Our kids' mattress range covers every one of those sizes, and we stock shorty mattresses in the correct 75 x 175cm size, which most retailers don't.
Bunk beds and high sleepers: check the depth
The most expensive mistake we see, and it happens most often at replacement time rather than at purchase.
Raised beds have a maximum mattress depth, usually 15 or 16cm. Guard rails are designed to sit a set height above the mattress surface. Put a 20cm mattress on there, which is what most supermarket and high-street singles are, and you've removed 5cm of guard rail. The rail is still there, but it isn't doing its job.
Two other things specific to bunks:
- Replace both at once. Two mattresses of different ages on the same bunk means one child on a good bed and one on a worn one. Buying together is cheaper and fairer.
- Trundles have their own limit, usually around 10cm, because the mattress has to clear the frame above when it slides away. A standard mattress won't fit.
Everything in our bunk bed mattress range is built at 15cm for exactly this reason, and the TrundleEase 10 is sized for pull-out beds.
Which mattress to replace it with
For a child, the choice is simpler than the adult market makes it look.
Memory foam
Contours to the body, good for restless sleepers, and quiet. Runs slightly warmer than sprung. Our MemoryDream 15 is the one most parents choose.
Pocket sprung
More airflow, so cooler, and a more traditional feel with a bit of bounce. Better for a child who sleeps hot. The PocketRest 15 covers this.
Reflex foam
Firmer and more supportive, and the most affordable of the three. Good for younger children and for a bed that won't get nightly use, like a guest or trundle bed. That's the ComfortSleep 15.
For older children and teenagers
If the bed isn't a bunk or high sleeper, the depth limit doesn't apply and you can go deeper for more comfort. The MemoryTeen 18 is built for that, at 18cm.
All of ours are made in the UK, arrive vacuum packed and rolled so they come upstairs easily, and are built to the correct depth for children's beds.
Making one last longer
- Use a protector from day one. The single biggest factor in how long a child's mattress survives, and it costs a fraction of replacing it.
- Rotate head to toe every three months. Most children's mattresses are single-sided, so rotate rather than flip unless the label says otherwise.
- Vacuum it monthly with the upholstery attachment.
- Air it regularly. Pull the bedding back for an hour in the morning rather than making the bed immediately.
- Deal with accidents the same day. Once urine dries in, the smell is far harder to remove. Our guide to removing urine smell from a mattress covers what actually works.
- Check the base. A sagging slat or a broken bed base will ruin a new mattress in months.
Common questions
How often should a child's mattress be replaced?
Every 5 to 7 years, or sooner if it's been outgrown, damaged or repeatedly soiled. The 7 to 10 year guidance you'll see elsewhere is written about adult mattresses.
Can I pass a mattress down to a younger sibling?
If it's in good condition and only a few years old, yes. If it's already done six or seven years, or been through accidents, you're giving the younger child a mattress that's near the end of its life. Check it properly rather than assuming.
My child's feet are near the end of the bed. How long have I got?
Roughly a year once they're within 10cm of the end. Worth planning the next size rather than waiting for it to become urgent.
Can I use any single mattress on a bunk bed?
No. Check the maximum depth for your bed, usually 15 or 16cm. Most standard singles are 20cm or more, which reduces the guard rail clearance.
Does a mattress protector really extend the life?
Considerably, on a child's bed. Most children's mattresses are replaced because of what's happened to them rather than because the foam has worn out.
How do I dispose of an old mattress?
Most councils collect bulky waste for a small fee, and household waste recycling centres take mattresses. Book it before the new one arrives so you're not storing both.
