A shorter pillow between the knees, for keeping hips level
Your answers point to a short, firm pillow that sits between your knees and keeps your top leg level with your hip.
Updated .
In short: A pillow about knee size, firm enough to hold your knees apart all night, does the aligning. A long body pillow is an optional extra.
The fit
Lengths and fills come from published maker dimensions and the sources cited on this site. This site measured nothing and gives no medical advice.
| Part | Specification | Source |
|---|---|---|
| Shape | A compact hourglass shape or a rectangle that fits between the knees. Published heights run from 4.5 in to 6.3 in. | BEDGEAR product page; Sleep Number product page; ComfiLife product page |
| Length | Knee pillows run from 9.5 in to 16 in long. Short natural body pillows come in 30 in and 40 in. A standard body pillow is 54 in. | Cushion Lab product page; Sleep Number product page; Sleep Sovereign product page; Coop size guide |
| Fill | Knee pillows use memory foam or shredded foam. Short body pillows also come in kapok, wool or shredded latex. | ComfiLife product page; BEDGEAR product page; Sleep Sovereign product page |
| Cover and washing | A zip-off cover that goes in the machine. A memory foam core is not washable. One kapok and latex pillow says to spot clean insert only. | Cushion Lab product page; MINICAMP product page |
| Where it goes in the bed | Between the knees with the legs drawn up slightly, or under the knees when you lie on your back. | Mayo Clinic |
Reading your answers back
Your first answer decided the shape. Keeping knees and hips lined up depends on what sits between the knees, and that space is small. Mayo Clinic advises that if you sleep on your side, draw your legs up slightly toward your chest and put a pillow between your legs. It says this can help align your spine, pelvis and hips, and that you can use a full-length body pillow if you prefer. Length is a matter of taste here.
Height counts for less here than on other results. A knee pillow only has to fill the gap between your knees, so a tall frame does not need a long one. Published knee pillows run from 9.5 in to 16 in long (Cushion Lab; Sleep Number). That fits any frame. One maker that lists two sizes suggests the larger one if you have a larger frame or want broader support between your knees and lower thighs.
For someone who stays on one side, the pillow stays where it was put. Turning through the night is harder. The pillow has to come over with each roll, or it ends up on the floor. That is the case for a U shape instead. Back sleepers can keep the same pillow, because Mayo Clinic suggests that if you sleep on your back, place a pillow under your knees.
A small or shared bed makes the case stronger. A knee pillow takes almost no width, while a standard body pillow is 20 in x 54 in, according to one maker's size guide. For a firm feel, foam holds a set thickness. For a soft feel, a natural fill you can push back into place suits better, and one maker lists natural fills in shorter lengths. Washing is simple at this size. The cover goes in the machine, but check the core first. One foam knee pillow says its removable cover is machine washable, but the memory foam core is not.
If your situation changes
If you also want something to hold, the answer moves to a short body pillow. In a Good Housekeeping trial, some testers found knee pillows helpful for alignment, while others thought they were too firm or too small and preferred a regular or full-size body pillow. That comes down to comfort. If back pain is your reason, read what a body pillow changes about how your back rests and ask a clinician. Side sleepers comparing the longer shapes can read how a body pillow keeps a side sleeper's hips and shoulders in line.
Trying the fit in your own bed
Lie on your side with the pillow in place. Your top knee should sit about level with your hip, so the thigh runs parallel to the mattress. If the knee drops, the pillow is too thin. If it rises, it is too thick. Then roll over once. Note whether the pillow came along or slid off the edge, and check again after a full night rather than just the first few minutes.
Other body pillow guides
- How does a body pillow keep a side sleeper's hips and shoulders in line?
- What does a body pillow change about how your back rests overnight?
- What category is a body pillow?
Back to which shape and length
Sources
Gathered here, the outside pages this body pillow guide quotes, each beside the part of the guide that needed it.
- BEDGEAR product page (bedgear.com), needed in “The fit”.
- Sleep Number product page (sleepnumber.com), needed in “The fit”; “Reading your answers back”.
- ComfiLife product page (comfilife.com), needed in “The fit”.
- Cushion Lab product page (thecushionlab.com), needed in “The fit”; “Reading your answers back”.
- Sleep Sovereign product page (sleepsovereign.net), needed in “The fit”; “Reading your answers back”.
- Coop size guide (coopsleepgoods.com), needed in “The fit”; “Reading your answers back”.
- MINICAMP product page (amazon.com), needed in “The fit”.
- Mayo Clinic (mayoclinic.org), needed in “The fit”; “Reading your answers back”.
- two sizes (pinetales.com), needed in “Reading your answers back”.
- Good Housekeeping trial (aol.com), needed in “If your situation changes”.