Best trundle beds
A trundle mattress is limited by the gap it has to slide back into, which is usually around 15 centimetres.
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A trundle is a second bed on castors that stores under the main one and pulls out when needed. It is the most space-efficient way to sleep two people in one bed's footprint.
The constraint is mechanical and it is not negotiable. The mattress has to fit back under the frame, which caps its depth, usually at around 15 centimetres and sometimes less.
That has one consequence worth being honest about: the lower bed will be a thinner mattress than the upper one, and at those depths firm works better than soft, because there is less material between the sleeper and the base.
The second thing to check is height. Unless the trundle pops up, the two beds sit at different levels.
The picks
The pick, if you want one answer
Simba Hybrid Kids Mattress, 7.6 / 10. A shallow mattress built for a child's weight, which is who most trundles are for.
| Product | Best for | From | Score |
|---|---|---|---|
| Simba Hybrid Kids Mattress | Best for a child | Mid range | 7.6 / 10 |
| Rem-Fit Kids Mattress | Best value | Budget to mid | 7.5 / 10 |
| Silentnight Sleep Now Range | Cheapest shallow option | From £169 | 6.7 / 10 |
| Silentnight Airmax Topper | Best way to improve a thin trundle mattress | Budget to mid | 7.4 / 10 |
Simba Hybrid Kids Mattress: Best for a child
Mid range · 7.6 / 10
Scores 7.6. A child barely compresses a mattress, so the reduced depth of a trundle matters far less to them than it would to an adult. Waterproofing and a washable cover matter more.
Buy it if
The trundle is for children, which most are.
Do not buy it if
It is for adult guests.
Read the full Simba Hybrid Kids Mattress review
Rem-Fit Kids Mattress: Best value
Budget to mid · 7.5 / 10
Scores 7.5. Rem-Fit's eligibility schemes are unusually broad, covering key workers, seniors and students, which can change the price more than the specification gap at this end.
Buy it if
You want a sensible children's specification at a lower price.
Do not buy it if
You need the absolute lowest price.
Read the full Rem-Fit Kids Mattress review
Silentnight Sleep Now Range: Cheapest shallow option
From £169 · 6.7 / 10
From a manufacturer trading since 1946. At shallow depths, firm is what makes a thin mattress work: you are not sinking far, so there is less need for the structure a thicker mattress provides.
Buy it if
You need a shallow mattress from a manufacturer that will still exist.
Do not buy it if
You want something deeper. A trundle will not take it.
Read the full Silentnight Sleep Now Range review
Silentnight Airmax Topper: Best way to improve a thin trundle mattress
Budget to mid · 7.4 / 10
Scores 7.4. A thin topper adds surface comfort without much depth, and spacer mesh is the thinnest useful option. Measure the clearance with the topper on, because it has to slide back in with everything on it or come off every time.
Buy it if
The trundle mattress is thinner than you would like for an adult guest.
Do not buy it if
The clearance is already tight.
Read the full Silentnight Airmax Topper review
Measure the clearance, with bedding on
The measurement people get wrong
Measure from the floor to the underside of the main bed frame, then subtract the trundle frame and castor height. What is left is your maximum mattress depth.
Then subtract a little more for bedding, because a made-up trundle has a sheet, a protector and sometimes a duvet on it, and it still has to slide home.
Most trundles end up with a maximum around 15 centimetres. A modern hybrid at 28 to 35 is out of the question, which is why trundle mattresses are their own category rather than a size choice.
The two beds will not be level
A standard trundle sits on castors at floor level, so the sleeping surface is considerably lower than the main bed.
Pop-up trundles have a mechanism that raises the lower bed to the same height, which turns two singles into a large sleeping surface. They cost more, add a mechanism that can fail, and are the right choice if two adults will share.
For children, the height difference rarely matters and the simpler frame is usually the better buy.
Check the castors against your flooring too: trundles run poorly on thick carpet, and a bed that is hard to pull out gets used less than one that glides.
Foam or springs at this depth
This is one of the few cases where foam has a genuine structural argument.
A sprung unit needs height to work: squeeze springs into 12 centimetres and they are short, stiff and do less. Foam works by material property rather than travel, so it performs better at very shallow depths.
Above about 15 centimetres, springs recover their advantage, because they move air and resist body impressions in a way foam does not.
If you do buy foam, density is what predicts how long it lasts, with decent comfort layers between 48 and 72 kilograms per cubic metre. Almost nobody publishes it, and at the cheap end that silence is informative rather than neutral.
Storing a bed under a bed
A trundle spends most of its life in a dark enclosed space with no airflow, which is the condition in which moisture collects.
Pull it out and air it periodically, even when nobody has slept on it, and particularly in winter. Standing the mattress on edge for an hour with a window open is enough.
Do not store it made up with a duvet for months, because that traps whatever moisture is in the mattress against it.
Fit a protector, because a mattress used by occasional guests is a mattress nobody will tell you about, and a stain voids most guarantees absolutely.
What not to do
Buy a mattress deeper than the clearance. Measure with bedding on.
Assume the two beds will be level. Only pop-up trundles are.
Buy a soft thin mattress. Firm is what makes shallow construction work.
Leave it stored made up for months. It traps moisture against the mattress.
Buy shallow foam with no published density.
Also considered, and why they are not here
A roundup is only as useful as what it leaves out, so here is what was assessed and rejected for this list.
| Product | Why it is not on the list |
|---|---|
| Emma Original Lite | Excellent at £199, and check the depth against the clearance before assuming it fits a trundle. |
| Inofia Tri-Fold | A folding mattress, which stores in a cupboard rather than under a bed and avoids the depth cap entirely. |
| Mlily Memory Gel 200 | Scores 5.5. Shallow foam fits the depth limit, and no published density means no way to judge how long it lasts. |
| Simba Hybrid Cot Bed | For a cot rather than a trundle. Cot mattresses follow safer sleep guidance, which is a separate set of rules. |
How this list is made, and who made it
Independence
No brand pays to appear on this site and no placement is sold. Some links earn a commission if you buy, which never changes a score, an order or a verdict. Several of the lowest scores here are on products that carry commission, and several recommendations carry none.
Who writes this. Kyle Klinkradt has worked in the mattress and bedding industry for over ten years across retail, distribution and brand partnerships, and has handled, sold or assessed products from every major UK bed-in-a-box brand. Every review on this site is written by one person, so the scores mean the same thing from page to page.
What the assessment is. Construction specifications against what they physically do: spring height and where in the mattress it sits, spring count for the size, gauge, whether the base is sprung or foam, foam density where it is published, comfort layer depth and material. Then the commercial terms that decide what you are actually buying: trial against returns policy, guarantee length against the company's UK trading history at Companies House, and the regulatory record.
What it is not. This is not a laboratory. I do not publish pressure-mapping data or claim to have slept eight years on every mattress here, because nobody has and pages that imply otherwise are not telling you the truth. Where a judgement rests on construction rather than long-term use, the review says so.
What gets a product removed. Leaving the UK market, a specification change that makes the review inaccurate, or a corrected fact. Brands that have withdrawn are kept on the site with the score removed rather than quietly deleted, because people still search for them.
See editorial independence, corrections and the author page.
How these were chosen
Every product here has its own review on this site with a score out of 10, and the score is a judgement rather than an average. Nothing appears in a list because it pays more.
A score is against the market, not against its own range. The cheapest mattress in a lineup is usually priced to make the model above it look reasonable, and the flagship of a budget range has risen into a bracket where better brands compete. Both are judged against what else you could buy for the money.
Everything listed can actually be bought in the UK. That is not a given: Casper withdrew in July 2020 and Leesa no longer sells here, and both still appear in current British roundups with affiliate links attached.
I do not pad the list. Where only three or four products genuinely qualify, there are three or four. A list of seven when the category contains four good ones is a list with three bad recommendations in it.
Prices move constantly. Judge the cash price on the day rather than any percentage beside it. See every review on this site or where the real savings are.
Questions people ask
What depth mattress fits a trundle bed?
Usually around 15 centimetres or less. Measure from the floor to the underside of the main bed frame, subtract the trundle frame and castor height, then subtract more for bedding, because it has to slide home made up.
Are trundle beds the same height as the main bed?
Not unless they pop up. A standard trundle sits on castors at floor level, so the sleeping surface is considerably lower. Pop-up mechanisms raise it level, which matters if two adults share.
Should a trundle mattress be foam or sprung?
Below about 15 centimetres, foam usually performs better, because springs need height to compress and recover. Above that, springs regain the advantage because they move air and resist impressions.
How do I look after a trundle mattress?
Pull it out and air it periodically even when unused, because it lives in a dark enclosed space with no airflow. Do not store it made up with a duvet for months, and fit a protector.