How to choose the right firmness

There is no standard for the firmness scale. What one manufacturer calls 6 out of 10 can be a 4 at another, and the number is chosen in marketing, not in a laboratory. The only useful reference points are your weight and the position you sleep in.

Position matters more than preference

On your side, the shoulder and hip need to sink in far enough for the spine to stay straight. Too firm and the spine curves upward; too soft and it sags. On your back, the lower back needs contact — if your hand slides easily under the small of your back, the mattress is too firm. On your front, firmer is almost always necessary so the hips do not drop.

Weight shifts the scale

The same mattress is softer under 200 pounds than under 130. Below 130, a ‘medium’ behaves like a firm one. Above 220, it behaves like a soft one and you start to feel the base layer. If two of you sleep on it with a large weight difference, a pocketed-coil hybrid handles that better than a block of foam.

The test at home

Sleep on it for thirty nights before you judge it. The first few nights on a new mattress are almost always uncomfortable, however good it is — your body has got used to a dip it can no longer find. Judge by how you get up in the morning, not by how it feels when you lie down at night.