A guide to pillow firmness

Key takeaways

• Firmness and loft are different things. Firmness is how much the pillow resists your head, and loft is how tall it is, but most pillows change both at once.

• Makers label firmness their own way. One down maker, Feathered Friends, changes the amount of fill, and one latex maker, Avocado, uses a foam-hardness number. We found no scale that brands share.

• We found no trial that tested firmness on its own. Studies compare whole pillow types that differ in height, shape, and material, and most enrolled side sleepers.

• For neck pain, the NHS suggests a low, firm pillow. It’s one self-care step on its page about neck pain, with no advice by sleeping position.

• The trade-off is mostly trial and error. Check that your head sits level with your spine in your usual position, and give a new pillow several nights.

What pillow firmness means

Firmness is how much a pillow pushes back when your head presses into it. Loft is its height. A pillow can be tall and soft, like a loosely filled down pillow, or low and firm, like a dense foam one, though in practice the two are tangled together. Adding more fill tends to make a pillow firmer and usually taller.

That’s visible in how makers describe them. Feathered Friends sells one down pillow, in the same 700+ fill power down, in three firmness levels, and the listed difference between them is the weight of the fill. In a Standard size the soft version holds 13 ounces, the medium 17, and the firm 22. Avocado makes a latex pillow in two versions rated 24 and 28 on a latex hardness scale. Its softer pillow is 4.5 inches tall and the medium one is 5.75, so height and firmness change together there as well.

How makers measure it

Fill power, the number printed on many down products, measures how much space an ounce of down fills, which is a quality measure. It doesn’t tell you how firm a finished pillow is, as the Feathered Friends example shows. Foam makers sometimes quote a number for how much force it takes to compress the foam, but that describes the foam, and we found no scale that brands share. For most pillows you get a word, soft, medium, or firm, that usually means whatever the maker decides.

Mattress studies have the same problem. A systematic review of 24 trials found that the firmness labels in the trials were subjective, even though medium-firm and self-adjusted mattresses tended to do best.

What studies say about pillows and neck pain

Researchers have tested pillow types more than firmness. In a 2009 field trial of 106 side sleepers, each person slept a week on their own pillow and on polyester, foam, feather, latex, and contoured foam pillows. The authors concluded that latex was best for waking neck pain, sleep quality, and comfort, that feather pillows should not be recommended, and that contoured foam was no better than regular foam. It relied on self-reports and ran one week per pillow.

The result didn’t carry over to people with neck problems. A 2019 pilot trial of people with confirmed neck degeneration found that no pillow changed any outcome by a statistically meaningful amount, and the authors said a properly powered trial would need 400 or more people.

A trial of 70 adults with long-lasting neck pain found less neck pain and headache after four weeks on a spring-and-foam pillow than after an education program, with the shoulder pain difference not statistically significant. It tested one design against advice.

How much height should a pillow have?

A small lab study points to shoulder width. In a study of 15 healthy young adults lying on their sides, neck and shoulder muscle activity was lowest when the pillow’s height equaled shoulder width, compared with half or one and a half times that. It was short, small, and in people without neck pain. A review of height research concluded that the best height can’t yet be identified from the evidence, for back or side sleepers.

Which firmness for which sleeper?

Some makers match firmness to sleeping position. Feathered Friends, for example, recommends its soft pillow for stomach sleepers, its medium for back sleepers, and its firm for back and side sleepers. That is a maker’s recommendation. Most of the pillow trials we found enrolled side sleepers or tested a side-lying position, and we found none in stomach sleepers, so the advice for them is reasoning. For side sleepers, the shoulder-width idea covers height, and firmness wasn’t tested.

The NHS page on neck pain lists using a low, firm pillow among self-care steps and advises seeing a GP if the pain doesn’t go away. The page names “low” and “firm” as two separate qualities, which is how this guide treats height and firmness.

Fill types, and what happens as they age

We found no study comparing how firmness holds up across fills, and the numbers makers publish are their own. Our guide to replacing your pillow covers lifespans by fill and how to check for wear.

Do contour and adjustable pillows help?

Contoured foam was no better than regular foam in the 2009 field trial above. A lab study of 20 healthy adults found less activity in a neck muscle during five minutes on their backs with a cervical support pillow than with a general pillow. We found no trial of shredded-fill adjustable pillows, where you remove fill to change height. A 2026 lab study of 30 healthy adults tested an air-based adjustable insert and rated it the most comfortable of six conditions, but it was a different design.

Does your mattress change the answer?

Probably, though we found no study that tests it. A softer mattress lets your shoulder sink, which could call for a lower pillow, and that’s reasoning. Our post on replacing your mattress covers wear that changes how the two work together.

How to choose and test a pillow

These are practical checks, not research findings. Lie in your usual sleeping position and see whether your head sits level with your spine and isn’t tipped up or down. Press the pillow and see whether it springs back. Give a new pillow several nights, since the first night in a different position isn’t a fair test. If you sleep in more than one position, a medium pillow is one way to split the difference.

If neck pain doesn’t go away, the NHS advises seeing a GP. If you’re pregnant, see our guide to sleeping better while pregnant.

The short version

Firmness is how much a pillow pushes back, and height is separate, though most pillows change both together. We found no trial that tested firmness alone, so the best test is how your neck feels in your usual position. For neck pain, the NHS suggests a low, firm pillow, and neck pain that persists calls for a doctor.

Frequently asked questions

What’s the difference between pillow firmness and loft?

Firmness is how much the pillow resists your head. Loft is its height. In fill pillows, more fill makes both go up.

Is a firm pillow better for neck pain?

The NHS suggests a low, firm pillow as a self-care step. Trials of pillow types have found mixed results, and one pilot trial in people with neck degeneration found that no pillow clearly changed outcomes overall.

What firmness is best for side, back, and stomach sleepers?

Some makers suggest firmer for side sleepers, medium for back, and soft for stomach. Most of the trials we found tested side sleepers, and we found none in stomach sleepers, so that advice isn’t backed by trial results.

Does fill power tell you how firm a pillow is?

No. Fill power measures the quality of the down. Firmness depends mostly on how much fill is inside.

How long should I try a new pillow?

We found no study on this. A few nights is a reasonable test, since a single night in a different position isn’t a fair test.