PillowFacts / Method

What a pillow is actually for, geometrically

Lying on your side, there is a gap between the side of your head and the mattress. Your shoulder sets how big that gap is. A pillow's only structural job is to fill that gap so your neck stays in line with the rest of your spine. Too little loft and your head hangs toward the mattress. Too much and it is pushed the other way. Everything else a pillow does — cooling, feel, shape — sits on top of getting that one distance right.

The arithmetic, in full

required_loft = neck_to_shoulder - mattress_sink

The pillow fills what your shoulder does not. A softer mattress swallows part of the gap, so you need less pillow — this is why the same pillow can be right in one bed and wrong in another.

Because mattress sink is itself a range, the answer is a range. Anything inside it is a reasonable target.

The check that keeps this honest. A mid-range adult (6.25″ neck-to-shoulder, medium mattress) comes out at 4.5–5.2″. Side-sleeper pillows on the market cluster at 5–6″. Those overlap. This band is computed from the dataset at build time, never typed by hand. It is the check that the model is not nonsense: a mid-range adult on a medium mattress should land where side-sleeper pillows actually cluster on the market, because that is where the market found its answer by trial and error. The arithmetic was not tuned to produce that agreement — it is a subtraction of two independently sourced ranges. A change to this model that stops landing near the market cluster is a wrong change, and the build gate will say so.

The full span across every combination of typical measurement and mattress firmness is much wider than the central case, and is also printed. A model that quotes only its flattering middle is hiding its own error bars. Across the whole typical range and every mattress firmness this model spans 2–7.1″ — far wider than the central case, which is the honest way to read it. A tall person on a firm mattress and a small person on a soft one genuinely do need different pillows, and most of the market sells to the middle.

Why your ear hurts, and why it is usually a loft problem wearing a disguise

Ear pain when side sleeping is normally a bottoming-out symptom. Your ear is the smallest contact patch carrying the largest share of your head's weight. Whether that hurts depends less on what is in your ear than on whether the pillow surface can still move underneath it.

Not enough loft

The pillow compresses to its dense base under the weight of your head. Once it has bottomed out, the surface stops behaving like foam and starts behaving like a table. The load that was spread across the side of your head concentrates on the ear.

How you can tell: Your neck also aches, and the pillow feels flat by morning even though it looked fine when you lay down.

Not enough soft layer to displace

Even at the right loft, the surface has to be able to move out of the way locally — around your ear, and around anything in it. If the top layer cannot displace further than the height of the object, the object gets pressed against a firm plane instead of sinking into a soft one.

How you can tell: The pillow feels supportive and your neck is fine, but there is a distinct sore spot exactly where the ear contacts.

Something in the ear that sticks out

Earbuds, hearing aids, foam plugs and healing jewellery all add a hard point to a surface that was already the smallest contact patch on your body. They do not create the problem; they reveal how little room the pillow had to give.

How you can tell: The same pillow is tolerable without the object and not with it.

Two families of answer

Remove the contact — the hole

Cut an opening so the ear touches nothing at all.

Strength	Directly and completely eliminates ear contact. Works regardless of what is in the ear.
Cost	The opening is removed from the surface that was supporting your head. Support around the hole is thinner, and shaping the pillow around an opening constrains what else it can do for your neck. You also have to find the hole in the dark, and stay on it.
Who it suits	People who need the contact gone outright — a fresh piercing, an object that cannot be compressed, or anyone who has already tried getting the loft right and still hurts.

Stop bottoming out — loft plus a conforming top layer

Get the loft right so your head is not driving the surface to its base, and use a surface with enough soft depth to displace around the ear.

Strength	Nothing is given up. The pillow is still doing its structural job for your neck, and the ear stops being the load-bearing point rather than being exempted from load.
Cost	It depends on your measurements and your mattress, so it is not one product for everyone. A pillow that solves it for one person can fail for another with different shoulders.
Who it suits	Most people, and specifically people who want one pillow that works whether or not there is anything in their ear that night.

Worth saying plainly. Every company selling into ear pain sells the hole, because every company selling into ear pain sells a pillow with a hole in it. The second family of answers is not absent because it fails. It is absent because nobody whose product is a hole has a reason to mention it.

Model version 1.0, updated 2026-09-05. The full dataset behind this page — including this model's parameters — is the same one the calculator and the comparison table read from.