Is the Sealy by Slumber King a good price at $709.99?

It is the only new price listed, $709.99 at Mattress Firm as of November 7, 2026. With no other new listings, compare it against other king foam mattresses in the $600 to $900 range before deciding.

Is medium firmness right for side sleepers?

Medium is a middle setting that suits many side sleepers, but lighter side sleepers often want softer foam at the shoulder and hip. Heavier sleepers may find it too soft and prefer a firm model.

Does it need a box spring?

No. A foam mattress like this works on a solid platform, slatted frame or adjustable base. A box spring is optional and mainly adds height.

How does it compare with a Sealy hybrid?

A hybrid adds coils under the foam, which usually means better edge support and a bouncier feel. This all-foam model is quieter and isolates motion better, at a lower price.

What size is the King?

A standard king measures 76 by 80 inches, the same footprint as most king beds. Check your room and frame before ordering, since a king needs a king-size base.

Mattress prices usually drop around major holiday sales. Track the price history on this page and buy when it falls below the current $709.99.

Where is the Sealy By Slumber Mattress King cheapest?

At Mattress Firm, for $709.99, as of our latest check.

Sealy By Slumber Mattress King

Best price now

$709.99at Mattress FirmObserved at 10:43 AM

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Our take on the Sealy By Slumber Mattress King

The Sealy by Slumber King is a medium-firmness foam mattress sold in king size, positioned as an entry-level Sealy. It uses a foam build rather than springs, so it suits sleepers who want a quiet, motion-isolating bed at a low price. At $709.99 at Mattress Firm as of November 7, 2026, it is the only new price listed, so there is no recent range to compare it against.