King Koil Plush vs Medium vs Firm - Which Mattress Firmness Is Right for You?
By Michael Morrison, General Manager, Best in Beds - Published
Multi-store mattress retailer with showrooms in Campbelltown, Prospect and Warrawong, NSW
In short: Every King Koil MK2 mattress is available in three comfort levels: Plush, Medium, and Firm. The support system underneath stays the same - what changes is the surface feel. Here's the honest, showroom-tested guide we use to match customers to the right one, organised by sleep position, weight, partner setup, and any back or joint issues.
Quick answer (if you only read one paragraph):
Medium is right for most people. Choose Plush if you're a side sleeper, lighter sleeper (under 75kg), or have shoulder/hip pressure issues. Choose Firm if you're a stomach sleeper, heavier back sleeper (90kg+), or specifically asked for a firmer mattress. If you're a couple with mixed preferences, Medium is almost always the right compromise.
What "firmness" actually means in a King Koil
People sometimes assume Plush means "soft and unsupportive" and Firm means "hard and uncomfortable". Neither is right - at least not for a properly-engineered mattress like King Koil.
Every King Koil MK2 model - Lexington, Chamberlane, Abelia, Kenwick - sits on the Reflex Support System (Primary coils + Active coils, individually pocketed, with Performa Edge). That support system stays the same across Plush, Medium, and Firm in the same range. What changes is the comfort layer feel at the surface:
- Plush - softer top layer, more pronounced sink, deeper contouring at the shoulders and hips.
- Medium - balanced surface, some give but not excessive sink. The most popular feel.
- Firm - less sink, more responsive surface, more "on top of" the mattress.
All three deliver the same chiropractor-approved support underneath. The right choice depends on the sleeper.
Pick by sleep position
Side sleepers → Plush (usually) or Medium
Side sleepers have a specific problem: the shoulder is the widest part of the body and the hip is the second widest, with the waist (narrowest) in between. For the spine to stay level, the shoulder and hip need to sink in slightly while the waist stays supported. A surface that's too firm leaves the shoulder and hip pressed against the mattress, creating pressure points and pushing the spine out of alignment.
Recommended: Plush for most side sleepers. Medium if you're a side-and-back combination sleeper.
Back sleepers → Medium (usually) or Firm
Back sleepers need the lumbar (lower back) supported so the natural curve of the spine is maintained. Medium provides this for most back sleepers - enough comfort layer to cushion pressure points without excessive sink that lets the lumbar arch.
Recommended: Medium for most back sleepers. Firm for heavier back sleepers (90kg+) or anyone with chronic lower back pain who's been advised to firm up the surface.
Stomach sleepers → Firm
Stomach sleepers face the highest risk of lumbar arching - if the surface allows the pelvis to sink too far, the lower back arches and pressure builds. Firm minimises that sink.
Recommended: Firm. Always. Stomach sleepers on Plush or Medium often wake up with lower back pain.
Combination sleepers → Medium
If you move between back, side, and stomach positions through the night, Medium is the safest answer - it's the most accommodating across all three positions.
Pick by weight
Body weight changes how much you sink into any mattress surface - and therefore how the surface feels.
- Under 75kg - Plush feels Plush, Medium feels Firm, Firm feels Very Firm. Most lighter sleepers do best on Plush or the softer end of Medium.
- 75-90kg - Surface feel is roughly as advertised. Medium is the right starting point for most.
- 90kg+ - Plush sinks faster, Medium feels softer than expected, Firm feels closer to Medium. Heavier sleepers usually do better on Medium or Firm than the labels suggest.
Pick by partner preference
If you're shopping as a couple with different firmness preferences, the practical reality is you have three options:
- Compromise on Medium. The most common choice and usually the right answer.
- Pick the firmness the heavier partner needs. Heavier sleepers feel less of the firmness difference; lighter sleepers feel more. If one of you is 90kg and one is 65kg, the 90kg sleeper's preferred firmness is usually the right ensemble compromise.
- Two separate mattresses (zip-and-link). Available on some configurations - talk to us in-store if this is a serious consideration.
Pick by back/joint issue
- Lower back pain (lumbar): Medium for most. Firm if heavier or stomach sleeper.
- Sciatica: Medium with deeper contouring comfort (e.g. Chamberlane Medium).
- Shoulder pain: Plush - almost always. The shoulder needs to sink in.
- Hip pain / arthritis: Plush, ideally with deeper contouring (Abelia Plush or Chamberlane Plush).
- Sciatica / disc issues + back sleeper: Medium with zoned support (Abelia or Lexington Medium).
For more detail, read our chiropractor-approved mattress guide.
The single best thing you can do: lie on one
Firmness is the one thing a website cannot accurately communicate. We can describe Plush, Medium, and Firm in words, but the only way to know which one is right for you is to lie on each for 10 minutes. The full King Koil MK2 range is on display in all three comfort levels at all three Best in Beds Sydney showrooms.
Bring your partner. Wear clothes you'd sleep in (or as close as you reasonably can). Get into your actual sleep position - don't just sit on the edge. Stay there for at least 5 minutes per mattress. After 4-5 mattresses, you'll know.
- Best in Beds Campbelltown - 20 Blaxland Road. 02 4628 1266
- Best in Beds Prospect - 27 Rowood Road. 02 8676 7321
- Best in Beds Warrawong - 91-95 King Street. 02 4274 3485
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Posted in
A.H. Beard, Brands, King Koil, Mattresses, Sleep Science
