How often should you change your mattress
Eight years is the number everyone repeats. The measurement that actually answers it takes thirty seconds.
The test that beats the rule
Lay a straight edge across the mattress and measure the gap at its deepest point. More than about 25 millimetres and it is finished, whatever its age.
A broom handle or a spirit level works. Do it with the bedding off.
The eight year rule is repeated everywhere, largely by people selling mattresses, and it is a poor guide because two mattresses of the same age are rarely in the same condition.
A well-made pocket sprung mattress on a proper base, used by one person of average build, can be sound at twelve years. Cheap foam on wide slats under two heavier people can be finished at four.
Realistic lifespans by construction
| Construction | Expect | How it fails |
|---|---|---|
| Cheap foam, density not published | 3 to 5 years | Compression set. Loses height invisibly. |
| Dense foam, 48 to 72 kg/m³ | 7 to 10 years | The same, considerably slower |
| Open coil | 7 to 10 years | The spring unit loses tension together |
| Pocket sprung | 8 to 12 years | Comfort layers go before the springs |
| Latex | 10 to 15 years | Resists compression set far longer |
| Hand-built natural fillings | 12 to 15 years | Settles, and can sometimes be re-tufted |
Why foam fails without looking any different
This is why people sleep badly for years without suspecting the mattress.
Polyurethane foam is a cellular plastic, and repeated compression gradually collapses the cell walls. That is compression set: the mattress loses height and support while looking identical. No visible sag, no lump, nothing to point at in a photograph.
Density predicts how long it takes, measured in kilograms per cubic metre, with decent comfort layers between 48 and 72. Almost no brand publishes it, and at the budget end that silence is informative rather than neutral.
Steel does not age this way. A pocket spring unit that has not been abused holds its geometry for a decade and more, which is why spring-supported mattresses generally outlast foam-supported ones bought for the same money.
The signs, in order of reliability
A measured dip over 25 millimetres. The only objective test on this page.
You wake with pain that eases within half an hour of getting up. That pattern is mechanical and points at the bed rather than at you.
You sleep noticeably better away from home. Hotels, spare rooms, holidays.
You can feel individual springs, or hear them.
You roll toward the middle on a shared bed, which means the centre has gone or the base has.
Visible mould. That is the end of it, because mould cannot reliably be removed from within fillings.
What is not reliable: age alone, and how the mattress looks. Both mislead.
Check these three before replacing anything
A surprising number of mattress complaints are not mattress complaints, and all three checks are free.
The slat gaps. Over about 7.5 centimetres and the base is causing the sagging. Plywood costs a few pounds and is the cheapest fix available. On a double or larger, check there is a centre rail with a leg to the floor, because a sagging centre rail feels exactly like a soft mattress.
Your pillow height. Neck and upper back ache is a pillow problem that routinely gets blamed on mattresses. Lie in your sleeping position for ten minutes and have someone look from behind: your neck should be a straight continuation of your spine.
Rotation. If it has never been turned head to foot, do that and give it a fortnight before deciding.
Making the next one last longer
Fit a protector from the first night. A stain voids most guarantees absolutely, and protection is the only mattress cleaning strategy that works.
Rotate head to foot every two to three months. Turn it over as well if it is double-sided, which most modern mattresses are not.
Measure the base before the mattress arrives, not after.
Air it. Every few months, standing on edge with a window open, and particularly if it sits on a solid platform base where moisture collects underneath.
Do not sit on the same edge daily. Edge support is where mattresses fail first and is rarely specified below about 400 pounds.
What the guarantee will and will not do
Mattress guarantees typically cover body impressions beyond a stated depth, commonly 25 to 30 millimetres measured with bedding removed. They typically exclude normal softening, stains of any kind, and damage caused by an unsuitable base.
Two of those three are within your control, which is the practical argument for a protector and a tape measure.
And a guarantee is worth only the company behind it. Four brands reviewed on this site have gone: Eve into administration in 2022, Brook + Wilde liquidated in 2023, and Casper and Leesa out of the UK market.
Your statutory rights sit with the retailer, not the manufacturer, for up to six years in England, Wales and Northern Ireland and five in Scotland, so keep the proof of purchase.
Disposing of the old one
A council bulky waste collection typically costs 20 to 40 pounds and usually requires getting the mattress to the kerb yourself.
Some retailers remove the old mattress on delivery, which has real cash value that never shows in a price comparison. Panda includes free recycling on mattress orders, any brand.
Do not leave a mattress out in the rain before collection: a soaked mattress is heavier, harder to move and frequently refused.
Related reading
Is it finished?
Buying the next one
How this site works
Nothing here is paid for by a brand. No manufacturer has copy approval, a preview, or the ability to change a score, and where a link earns a commission that never changes a ranking.
Where a brand does not publish a specification, that is stated rather than estimated, because an absent number is itself information. The corrections log and the products I will not recommend page are both public.
Questions people ask
How often should you replace a mattress?
Measure rather than count years. Lay a straight edge across it and measure the deepest gap: more than about 25 millimetres and it is finished whatever its age. Pocket sprung runs 8 to 12 years, cheap foam 3 to 5.
Is the eight year rule accurate?
Not very. Two mattresses of the same age are rarely in the same condition, because construction, body weight, the base and rotation all change the outcome more than time does.
Why does my mattress feel worn out but look fine?
Foam fails by compression set: the cell walls gradually collapse so it loses height and support while looking identical. Density predicts how long that takes and almost no brand publishes it.
What should I check before buying a new mattress?
Slat gaps over about 7.5 centimetres, your pillow height, and whether the mattress has ever been rotated. All three are free and any of them can resolve what looks like a mattress problem.
How do I dispose of an old mattress in the UK?
A council bulky waste collection typically costs 20 to 40 pounds and usually requires getting it to the kerb yourself. Some retailers take the old one away on delivery.