Best knee pillows
A knee pillow does one mechanical job: it stops your top leg falling forward and twisting your spine.
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Lie on your side and your top leg is unsupported. Gravity pulls it forward and down, which rotates your pelvis while your shoulders stay put, so your spine twists along its length for the whole night.
A knee pillow holds that leg at roughly hip height, which stops the rotation. That is the entire mechanism, and some side sleepers get more relief from it than from a new mattress.
Test it free before buying anything. Fold a spare duvet or a pillow between your knees and sleep like that for a week. If it helps, a proper knee pillow helps more because it stays where you put it. If it does nothing, it will not either.
And one important distinction: if your hip aches on the side you lie on, that is usually the mattress being too firm, not a knee problem.
The picks
The pick, if you want one answer
Simba Body Pillow, 7.4 / 10. Holds shape and position under a leg all night, which is the only thing separating a knee pillow from a folded duvet.
| Product | Best for | From | Score |
|---|---|---|---|
| Simba Body Pillow | Best overall | Mid range | 7.4 / 10 |
| Kally Sleep Body | Best value | Budget to mid | 7.3 / 10 |
| Simba Hybrid Pillow | The head pillow that matters alongside it | Mid range | 7.9 / 10 |
| Simba Mattress Topper | If the hip is the actual problem | Mid range | 7.5 / 10 |
Simba Body Pillow: Best overall
Mid range · 7.4 / 10
Scores 7.4. A full-length body pillow does the knee job and gives your top arm somewhere to rest, which stops you rolling forward onto your front. Holding shape under a leg for eight hours is where cheap fibre-filled wedges fail: they compress and shift, and by 3am they are somewhere else.
Buy it if
The folded duvet test helped and you want something that stays put.
Do not buy it if
You want something small that stays between the knees only.
Read the full Simba Body Pillow review
Kally Sleep Body: Best value
Budget to mid · 7.3 / 10
Scores 7.3. A reasonable entry point into a format a lot of people try and then use differently from how they expected, most often as a front-leaning support rather than purely between the knees.
Buy it if
You want to spend less while finding out whether the format suits you.
Do not buy it if
You want the firmest possible support.
Read the full Kally Sleep Body review
Simba Hybrid Pillow: The head pillow that matters alongside it
Mid range · 7.9 / 10
Scores 7.9, the highest pillow score on this site. A knee pillow fixes the lower half and does nothing for the gap your shoulder creates at the head, which is the largest of any sleeping position and needs the most pillow height.
Buy it if
Your knees are sorted and your neck still aches in the morning.
Do not buy it if
Your head pillow height is already right.
Read the full Simba Hybrid Pillow review
Simba Mattress Topper: If the hip is the actual problem
Mid range · 7.5 / 10
The highest scoring topper here at 7.5. Hip pain when side sleeping usually means the mattress is too firm, so the shoulder and hip cannot sink in. No knee pillow fixes a surface that will not let the hip drop.
Buy it if
Your hip aches on the side you lie on and the mattress is sound.
Do not buy it if
The mattress has a dip over about 25 millimetres.
Read the full Simba Mattress Topper review
Getting the position right
The aim is the top leg at roughly hip height, so the thigh runs level rather than angling down toward the mattress.
Too low and the pelvis still rotates, which is the whole problem you are solving. Too high and you create a twist in the other direction, which is why stacking two pillows between the knees rarely works.
The pillow should sit between the knees and ideally down to the ankles, because supporting only the knee leaves the lower leg hanging and the rotation partly returns. This is why full-length body pillows work better than small wedges for many people.
Give it a fortnight. Changing sleeping position is uncomfortable for the first few nights regardless of whether the change is a good one.
Which symptom points where
| What you notice | Usually means |
|---|---|
| Lower back ache that eases as you move | Pelvic rotation, or a mattress too soft. Try the knee pillow. |
| Hip pain on the side you lie on | Mattress too firm. The hip cannot sink in. |
| Shoulder pain or a numb arm | Pillow too low, or mattress too firm at the shoulder. |
| Knee-on-knee discomfort itself | Exactly what a knee pillow is for. |
| Pain worse after standing, better lying down | Not a bedding pattern. Worth raising with a clinician. |
The second row matters most, because it sends people to the wrong product. A knee pillow cannot make a hard mattress let your hip sink.
Shapes, and why simple usually wins
A straight bolster supports knees and ankles together and doubles as something to lean into. The most versatile shape and the easiest to reposition.
A contoured or hourglass wedge sits between the knees only. Small, cheap and it moves, because there is nothing holding it in place when you turn over.
A strapped knee pillow stays put and some people find the strap itself uncomfortable.
If you share a bed, bed width is the real constraint. In a UK double each person has 67.5 centimetres, and a full-length pillow takes a noticeable share of it. In a king it is 75 centimetres each, which is workable.
What the fill needs to do
Firm enough to hold under a leg. Soft fibre fill compresses within weeks and stops doing the job, which is the commonest reason a knee pillow ends up in a cupboard.
A removable washable cover. It sits between your legs all night and the pillow itself usually cannot be machine washed.
Not too warm. Dense foam between your legs adds heat in a spot where air does not circulate. If you sleep hot, look for a cover that moves moisture rather than a plain synthetic one.
What not to do
Buy before the folded duvet test. A week costs nothing and tells you whether the mechanism helps you.
Lift the top leg higher than hip level. Too high creates its own twist.
Buy a soft fibre-filled wedge. It compresses under a leg within weeks.
Use one to fix hip pain from a too-firm mattress. That is a surface problem.
Buy a full-length pillow for a shared double. Each person has 67.5 centimetres.
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 |
|---|---|
| Aeyla Dual Pillow | A head pillow with two firmness options, useful alongside a knee pillow while you work out what height side sleeping needs. |
| Simba Hybrid Firm | A head pillow for side sleepers with broad shoulders. Named because the head end is what people most often leave unsolved. |
| Silentnight Airmax Topper | Scores 7.4. If the hip is the problem rather than the knees, a topper is the intervention, and this one softens without adding heat. |
| Soft fibre-filled knee wedges | Widely sold and pleasant in the shop. They compress under a leg within weeks, which is the one job the pillow exists to do. |
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 does a knee pillow actually do?
It holds your top leg at roughly hip height when you sleep on your side. Without it the leg falls forward and rotates your pelvis while your shoulders stay put, twisting your spine along its length all night.
How do I know if a knee pillow will help?
Fold a spare duvet between your knees and sleep like that for a week. If it helps, a proper knee pillow helps more because it stays where you put it. If it does nothing, a knee pillow will not change that.
Why do my hips hurt when I sleep on my side?
Usually a mattress too firm to let the hip sink in, which no knee pillow fixes. If the mattress has no dip over about 25 millimetres, a topper is the cheaper solution.
Should a knee pillow go between the knees or lower?
Between the knees and ideally down to the ankles, because supporting only the knee leaves the lower leg hanging and the rotation partly returns. That is why full-length bolsters work better than small wedges for many people.