Firmness and edge support

We do not rank mattresses by firmness, and this page explains why — and what we would look at instead.

Firmness labels are not a measurement

Medium, medium-firm and firm are marketing terms. There is no industry scale behind them and no requirement to be consistent, so one manufacturer's medium firm can be another's firm. A number of retailers publish a one-to-ten scale, but each publishes their own, calibrated by nobody.

That is why our rubric caps firmness disclosure at seven out of ten even for mattresses that state a firmness clearly: they have told you something, and what they told you is not comparable with what anybody else told you. Our full rubric.

Edge support is the spec that matters here

Nearly everything on this site is about getting into and out of bed. That movement happens entirely at the edge of the mattress — you sit on the perimeter, you take your full weight there, and you push up from there. What the middle of the mattress does at that moment is irrelevant.

A mattress with a soft edge does three unhelpful things:

• It lowers your effective bed height by however far you sink — often an inch or two, which is enough to undo a carefully measured setup. Which is why you measure compressed.
• It rolls away under you, so you slide forward as you sit rather than settling, and your feet arrive on the floor before you meant them to.
• It makes a bed rail's gaps worse. A soft edge compresses under and beside a rail, opening the rail-to-mattress gap that the FDA's guidance is about.

How to test it yourself

1. Sit on the very edge of the mattress, exactly where you get in and out, feet on the floor.
2. Notice how far you sink. More than an inch or two and the edge is soft.
3. Notice whether you feel pulled forward. If the edge is rolling away under you, that is the failure mode that matters.
4. Stand up. If you have to shuffle back onto firmer mattress before you can push up, the edge is not doing its job.

Do this on your current mattress before buying anything. It is a common cause of the complaint people describe as the bed being too low, and if it is the cause, risers will not fix it.

What to do about a soft edge

The middle matters too, but differently

A dip in the middle of a mattress means you sleep in a hollow and have to climb up out of it to get to the edge. That is a support failure and it is not fixable from above — a topper will follow the dip rather than fill it. The straight-edge test on that page takes thirty seconds and tells you which problem you have.