Split Tension Mattresses: Half and Half Guide
By Kaiser Khan, Editor Updated First published
Desk research from official sources. Not a product test or medical advice. How we check facts.
In short
A split tension mattress is one mattress with two spring-tension or firmness bands, one for each sleeper. Shops also call it a half and half or dual firmness mattress. A zip and link bed is different: two mattresses joined with a zip. Ask whether you are buying one unit or two, and check the UK size.
- Split tension
- One unit
- Zip-and-link
- Two units
- The shop words
- Not a law
- A common one-piece limit
- One step apart
- Head-to-foot rotation
- Sides swap
Two bands inside one mattress and one cover.
Two mattresses joined. Can mix types and go up stairs apart.
Dual firmness and half-and-half are catalogue names, not a British Standard.
Some makers pair soft with medium, or medium with firm, but not soft with firm.
Rotating moves each band to the other sleeper. Check the maker's care guide.
About 7 minutes to read
How it works
What is a split tension mattress?
A split tension mattress is one mattress with two spring-tension or firmness bands. One sleeper gets one band. The other sleeper gets the other. Spring tension means how hard the springs push back.
The join sits inside one cover. You still buy one UK plan size. A King is 150 × 200 cm. A Super King is 180 × 200 cm. Write those centimetres before you talk about “his and hers”.
This page is education. It is not a ranking. Big UK shops sell this idea to couples. We explain the build. We do not pick a brand.
Is a split tension mattress the same as a half and half mattress?
Usually, yes. Half and half, dual firmness and dual tension are shop names for the same idea. It means one mattress with a different band on each side. None of those words is a British Standard.
Shops do not always use the words the same way. At least one big UK shop page uses “split tension” for two mattresses zipped together. So ask one simple question: is this one mattress or two?
In short: the name matters less than the build.
Will I feel a gap in the middle?
No gap, because it is one mattress under one cover. There is no zip and no space between two edges.
You may still feel the change from one band to the other. That happens most if you lie across the middle. If you each keep to your own side, you may not notice it.
Some makers limit how far apart the bands can be. They pair soft with medium, or medium with firm. They do not pair soft with firm in one piece. They say a big gap can make one side sit lower. If you want soft and firm, some makers point you to zip and link instead.
What sizes do split tension mattresses come in?
A split tension mattress is one mattress. So it comes in normal UK sizes. Couples mostly choose a King or a Super King.
| UK size | Whole mattress (cm) | Each sleeper’s side (about) |
|---|---|---|
| King | 150 × 200 | 75 cm wide |
| Super King | 180 × 200 | 90 cm wide |
| Emperor (some makers) | often 200 × 200 | 100 cm wide |
Each side is part of one mattress. It is not a separate Single. It does not come apart.
Makers differ on smaller sizes. Some only make split tension from King upwards. Others list it from Small Single to Emperor. Check the maker’s size list. See UK standard bed sizes.
How do you turn or rotate a split tension mattress?
This is the tricky part. A normal rotation swaps the two sides.
Rotate means spin the mattress so the head end goes to the foot end. The same face stays on top. Picture it from the foot of the bed. The firm band is on your left. Spin the mattress round. Now the firm band is on your right. Each sleeper now lies on the other person’s band.
Flip end over end is different. The head end goes to the foot, and the underside comes up. Each band stays on its own side. This only works on a two-sided mattress. Two-sided means both faces are made to sleep on.
A one-sided mattress (also called no-turn) cannot be flipped. So a head-to-foot rotation will swap the bands. Ask the maker how they want it cared for. Some makers say to flip, not rotate, so you keep your side. Write their answer down before you buy.
Check the maker’s care guide. With no maker instructions, UK bed-industry advice is to move a mattress weekly for three months. After that, move it monthly. See turning vs rotating.
Split tension vs zip and link: what is the difference?
Zip and link is two mattresses joined with a zip or a link strip. Each half can have different support. A Super King zip and link set is usually two 90 × 200 cm halves. A standard UK Single is only 90 × 190 cm. Two of them come up 10 cm short of a Super King. Ask for the size of each half before you order. See zip and link mattresses.
| Question | Split tension | Zip-and-link |
|---|---|---|
| How many mattresses? | One | Two |
| Can types differ? | Usually no — one stack, two bands | Yes — pocket on one side, foam on the other if sold that way |
| Soft one side, firm the other? | Some makers keep bands one step apart | Often possible |
| Stairs | One large object | Two smaller objects |
| Centre feel | A change in feel under one cover | A zip; a bridge pad can soften it |
| Rotating | Swaps the bands between sleepers | Each half is unzipped and cared for on its own |
| Adjustable base | Only if the whole unit flexes | Easier on dual motors |
In short: ask “one unit or two?” before you ask “soft and firm”.
A side-by-side sits at split tension vs zip-and-link.
Why do UK shops push this for couples?
Partners do not share body weight. They do not always share sleep position. Soft, medium and firm labels mix spring tension and top feel. A “medium” compromise can leave one person perched and the other bottomed out.
Split tension tries to keep one bed and two support bands. It does not fix heat, snoring, or a mattress that is too narrow. A UK Double is still 135 cm wide. Two adults still get about 67.5 cm each.
Motion is a separate question. Pocket sprung and foam damp partner movement in different ways. See motion isolation. A split unit can still pass bounce across the join.
What should I ask before I pay?
- Is this one mattress or two zipped together?
- Is the split spring tension, top feel, or both?
- Which UK size is the whole plan, in centimetres?
- Which tension band is aimed at which body weight?
- Is it one-sided or two-sided? How do I keep my side when I rotate it?
- Does the warranty treat the join as one product?
- What base and slat gap does the warranty allow?
We do not publish a stone-to-tension chart. John Lewis, Dreams and handmade makers use different bands. Ask the maker which tension they intend for your weight. See questions to ask in a bed shop.
Who should skip split tension?
Skip it if both of you already like the same support band. A well-chosen single tension is simpler. Skip it if you need two constructions, not two tensions — use zip-and-link. Skip it if the stairs will not take a Super King in one piece.
Skip any page that says split tension treats back pain. That is a medical claim. We will not make it. See support claims.
Related BedGuide entries
Frequently asked questions
What is a split tension mattress?
It is one mattress with two support or firmness bands, one for each sleeper. Shops also say dual firmness or half-and-half. The join is inside one cover. It is not the same as two mattresses zipped together.
Is a half and half mattress the same as split tension?
Usually yes. Half and half, dual firmness and dual tension are shop names for one mattress with two bands. Some shops use the words loosely, so ask if it is one mattress or two.
Is split tension the same as zip-and-link?
No. Split tension is usually one mattress. Zip-and-link is two mattresses joined with a zip. Zip-and-link can mix types and is easier on narrow stairs. Split tension looks more like one bed. Ask which build you have.
Will I feel a gap in the middle of a split tension mattress?
There is no gap, because it is one mattress under one cover. If you lie across the middle, you may feel the change from one band to the other.
Who needs a split tension mattress?
Couples whose body weights or liked firmness bands sit far apart, and who still want one cover and one plan size. If you also need two constructions, or you cannot get a Super King up the stairs, look at zip-and-link first.
What UK size is a split tension mattress?
It is still a named UK plan. A King is 150 × 200 cm. A Super King is 180 × 200 cm. Each half is not a full Single unless the ticket says so. Write the whole centimetre pair, then ask how the join is built.
How do you rotate a split tension mattress without swapping sides?
A head-to-foot rotation moves each band to the other sleeper. On a two-sided mattress, flipping it end over end keeps each band on its side. Check the maker's care guide first.
Where do these facts come from?
BedGuide is desk research. The numbers and rules on this page were checked against the official or primary sources below. We name the check date. We do not invent a figure when a source is missing.
- National Bed Federation — regulations and standards — UK size names are industry practice, not a legal scorecard. Split-tension labels are shop language on top of those names. Checked 2026-08-28.
- IKEA UK mattress size guide — Reminds you to lock centimetres first. A dual-feel story does not fix a 150 cm mattress on a 160 cm frame. Checked 2026-08-28.
- John Ryan By Design — split tension mattresses explained (UK maker) — Offers one-piece splits as soft and medium or medium and firm only. Says the mattress can be flipped, not rotated, if you want to keep your side. Checked 2026-09-25.
- Feather & Black — split tension mattresses FAQ — States split tension bands can only be one category apart, such as soft and medium, because a bigger gap can make the surface uneven. Checked 2026-09-25.
- Dreams — split tension mattresses — Lists split tension from Small Single to Emperor, with King and Super King most popular. Its page uses the term for both zipped and one-piece builds. Checked 2026-09-25.
- National Bed Federation Bed Advice — caring for your bed — Without maker instructions: rotate one-sided mattresses weekly for three months, then monthly. Alternate rotating and flipping two-sided ones. Checked 2026-09-25.