Buying Better

Start with what the figure refers to. If a mattress lists a weight limit, check whether it covers one sleeper or the whole bed, whether it's fit guidance or a warranty condition, and what it's based on. A weight figure by itself doesn't tell you how the mattress will handle that load night after night.

Start with the written terms. Look for any body-weight or combined-weight conditions, foundation requirements, sagging thresholds, and definitions of normal use. A warranty describes coverage and exclusions; it does not predict how long a mattress will hold up.

Because firmness is an interaction, not a fixed property. The same surface responds differently to different bodies and positions — and reviews for one name often pool several variants. “A brick” and “quicksand” can both be honest reports.

Both can be true at the same time. A warranty measures a visible dip on an empty bed. What you feel is support under load, and support can fade before a visible dip appears. “Within tolerance” and “sagging” can describe the same mattress.

Good care helps at the margins and catches small problems early. What it can't do is reverse material fatigue in the center — that's a structural question, not a behavioral one. Rotation helps in narrower cases than most advice suggests.

Plywood is a reasonable fix for a foundation problem — wide slat gaps, a flexing frame, a sagging box spring. It won't restore a mattress that's lost support in its own core. Check the warranty terms before adding anything underneath.

There's no single correct number. The spacing your mattress needs is set by its manufacturer, and some warranties name it as a condition of coverage. Whatever the figure, a foundation that doesn't hold the mattress evenly can feel much like a change in the mattress's own support.