Working out the loft you need
Loft is the pillow's height under load, and for back sleeping it is close to the only spec that matters. Two things set it, and most guidance only mentions the first.
Your neck curve.Lie flat on your back on the floor with no pillow and have someone slide a hand into the gap behind your neck. That gap is roughly what you are filling. For most adults it is small — somewhere between one and three inches — which is why our top pick is 2.75 inches and why so many standard pillows are wrong for this position. If you spend part of the night face down there is no gap at all to fill, and the answer is flatter still — our stomach-sleeper pillow picks start at 1.75 inches.
Your mattress.This is the part people miss, and the Cleveland Clinic's guidance is explicit about it: the right pillow thickness depends on how firm your bed is. A firm mattress does not let your shoulders and ribcage sink at all, so the gap behind your neck stays at its full depth and you need more pillow. A soft mattress lets your torso settle in, which closes the gap, and you need less. The same pillow that is right on a firm bed is too tall on a plush one — so if you have recently changed mattress and your neck started hurting, that is very likely the cause rather than the new bed itself.
Fixed loft, adjustable loft, or contour?
Fixed low-profile
A single slab of foam at a published height. The advantage is precision: you know exactly what you are getting, and a maker that publishes an exact figure rather than the word “low” is giving you something you can plan around. The disadvantage is that if the number is wrong for you, there is nothing to adjust — you exchange it. Choosing from a line that offers several heights takes most of the risk out of that.
Adjustable fill
A shredded-foam pillow you can unzip and remove fill from until it sits where you want. For a back sleeper this is genuinely useful, because it lets you tune the pillow to your mattress rather than guessing. It is also the right answer if you switch between back and side during the night, and the only answer if you are buying a pillow without being able to try it.
The trade-off is that shredded fill shifts under load. It can migrate away from where your head sits, so it needs an occasional shake, and it never gives the precise, unchanging surface a molded pillow does.
Cervical contour
A molded shape with a raised ridge for the neck and a dip for the head. When the shape fits you it works very well, because it supports the neck curve actively rather than just filling the gap. When it does not fit you it is uncomfortable in a way you cannot adjust away, and there is an adjustment period even when it is right — a fortnight of feeling odd is normal, which makes it hard to judge in the first few nights.
Most contour pillows, including two of ours, have two different heights on opposite edges. The lower side is the back-sleeping side. People routinely use the taller one because it feels more substantial, and then conclude the pillow does not work. Our neck pain roundup covers the contour options in more depth.
If you also want to sleep on your side
Very few people hold one position all night, and this is where fixed low-loft pillows genuinely struggle: 2.75 inches is right for your back and far too flat for your side, where the shoulder creates a much larger gap. There are two workable answers.
The first is an adjustable pillow set to a compromise height — a little tall for back sleeping, a little short for side. The second is a dual-height contour, using the low edge when you are on your back and the high one when you roll. Neither is perfect, and anyone claiming a single pillow is optimal for both positions is overselling. Our side-sleeper pillow page covers the other end of the range if side sleeping is actually your dominant position.
The pillow under your knees matters too
Worth saying on a page about back sleeping, because the head pillow is only half of it. Lying flat leaves your lower back bridging a gap above the mattress, and over a full night that unsupported arch is tiring — it is the reason many people cannot stay on their back even when they want to.
The Cleveland Clinic's advice is to put a small pillow under the knees, which rotates the pelvis and lets the lumbar spine settle flat into the bed. It costs about thirty dollars and it is frequently the difference between back sleeping being comfortable and being something you give up on by 2 a.m. Our knee pillow picks include a low bolster made for exactly this.
Certifications in this category
A pillow is the one piece of sleep gear directly against your face for hours, so this matters more here than almost anywhere else on the site. Three of our four picks name CertiPUR-US certified foam. Worth knowing what that covers and what it does not: it tests the flexible polyurethane foam for restricted substances, low VOC emissions and restricted flame retardants. It says nothing about the cover, which is the layer actually touching your skin — that is what OEKO-TEX certification covers, and it is rarer on pillows than it should be. The certification decoder sets out the scope of each.
