Split King Mattress Explained

A split king mattress is a bed configuration made up of two separate mattresses (in Australia, typically two King Single mattresses, each 107 × 203 cm) placed side-by-side on a bed base sized to accommodate the pairing, giving a total sleep surface of about 214 × 203 cm. It lets couples choose different firmnesses on each side and, when paired with an adjustable base, control head and foot elevation independently. Below we cover what a split king is, how it compares to a standard king and to two separate King Singles, who it suits, and how it works with adjustable bases.

Key Takeaways

• A split king mattress is two separate mattresses (usually two King Single, 107 × 203 cm each) placed side-by-side on a bed base sized to accommodate the pairing, giving a total sleep surface of about 214 × 203 cm

• A split king differs from a standard king (183 × 203 cm) in three key ways: two mattresses instead of one, wider sleep surface, and independent-firmness compatibility

• Australia's split king pairs two King Singles; the US convention pairs two Twin XL (99 × 203 cm each), which has no direct Australian size equivalent

• Best suited to couples with different firmness needs, hot-and-cold sleeping pairs, and adjustable-base users who want independent head and foot control

• Our Koala mattress range is available in King Single sizes across all 5 models, so you can pair two matching mattresses or two different firmnesses to build your split king

What Is a Split King Mattress?

A split king mattress is a bed setup of two separate mattresses placed side-by-side to create a large king-sized sleep surface, most commonly used with adjustable bed bases where each partner controls their own head and foot elevation independently. In Australia, the two mattresses are usually King Single size (107 × 203 cm each), giving a total split king sleep surface of about 214 × 203 cm.

Key features of a split king:

• Two separate mattresses, not one large mattress with a "soft side and firm side"

• Total sleep surface typically 214 × 203 cm (2× King Single) in Australia

• A visible middle join that can be covered with a bridge pad or split-king fitted sheet

• Each side can carry a different firmness, feel, or cooling technology so the setup matches each partner's preference

• Commonly paired with adjustable bed bases for independent head and foot control

• Compatible with fixed bases sized to accommodate two King Single mattresses side-by-side

The split king setup is designed for couples who don't sleep the same way. Rather than compromising on one shared mattress, each partner gets a sleep surface tuned to their body, sleep position and temperature preference.

Split King vs King Mattress at a Glance

Split king and standard king serve different couples. A standard king is one mattress across a 183 × 203 cm sleep surface, ideal for couples with similar preferences. A split king pairs two separate mattresses on a wider base (about 214 × 203 cm), ideal for couples with different firmness needs or adjustable-base users. Here's how they compare across the factors that matter most.

The trade-off is straightforward: split king delivers customisation and independent adjustability at a higher upfront cost; standard king delivers cohesion and lower cost when both partners agree on feel.

Split King vs 2 King Single Mattresses

A split king in Australia is physically identical to two King Single mattresses; the difference is how the mattresses are set up and used. "Split king" means the two mattresses form one bed on a shared base with king-sized bedding (or split-king linen); "two King Single mattresses" implies the mattresses are used as two independent beds in a guest room or kids' shared room, each with its own fitted sheet and separate base.

The two setups compared:

• Split king setup: two King Single mattresses placed on a shared bed base sized for the pairing, with a bridge pad or split-king fitted sheet joining the two sides visually

• Two independent King Singles: same physical mattresses but placed on two separate bed bases in the same or different rooms, each with individual fitted sheets and separate bedding

The AU-vs-US size distinction:

• Australian split king: 2× King Single (107 × 203 cm each), total 214 × 203 cm

• US split king: 2× Twin XL (99 × 203 cm each), total 198 × 203 cm

• US Twin XL has no direct AU size equivalent: the closest AU size is King Single, which is 8 cm wider per mattress

• Practical implication: if you're reading US split king content, mentally translate Twin XL to King Single for AU compatibility, and expect the AU split king to be about 16 cm wider overall

Who Needs a Split King Mattress

A split king mattress suits couples with different firmness preferences, adjustable-base users who want independent head and foot elevation, hot-and-cold sleeping partners with different temperature needs, and anyone with a sleep-affecting health condition on one side of the bed (reflux, snoring, circulation, lower-back pain). It's less suitable for couples who cuddle across the middle of the bed, buyers on a tight budget, or bedrooms that can't accommodate the wider footprint.

Split king suits:

• Couples with genuinely different firmness needs: one partner prefers firm, one prefers plush; each picks their preferred model

• Adjustable-base users: independent head-up for reading or watching TV, foot-up for circulation, custom sleep-position support

• Hot-and-cold sleeping partners: one side can pair with cooling-focused technology (like our Koala Polar+ with PolarBands®), the other with a warmer setup

• Anyone with sleep-affecting health conditions on one side: reflux (head elevation), snoring (head elevation), poor circulation (foot elevation), lower-back pain (adjustable positioning)

• Couples who research sleep individually: split king respects that partners have different bodies, weights, sleep positions and health considerations

Less suitable for:

• Couples who cuddle across the middle of the bed: the join between the two mattresses can be felt, especially without a bridge pad

• Buyers on a tight budget: two mattresses cost noticeably more than one large mattress

• Small bedrooms: the 214 × 203 cm footprint doesn't fit rooms sized for a standard king (183 × 203 cm)

• Buyers who move house frequently: two mattresses are harder to transport than one

Split King & Adjustable Bed Bases

A split king delivers its biggest value when paired with an adjustable bed base that has independently articulating sides, so each partner can raise their head or feet without affecting the other. Standard fixed bases work fine too but only unlock the "different firmness" benefit, not the "independent adjustability" benefit.

The three split king base scenarios:

• Split-king adjustable base (two motors, two sides): each side raises head and feet independently. This is the ideal setup that unlocks the full split king benefit for adjustable-base users

• Full-king adjustable base (one motor, both sides move together): both sides adjust simultaneously; you keep the different-firmness benefit but lose the independent-adjustability benefit

• Fixed base sized for split king (no adjustability): uses the split king configuration only for the different-firmness benefit and improved motion isolation

Base compatibility considerations:

• Base width must accommodate 2× King Single: typically 214 cm wide, not a standard King (183 cm)

• Weight capacity: should support two adults on independently articulating sides

• Motor and remote configuration: corded vs wireless remotes matter for daily use practicality

• Warranty: adjustable bases have moving parts; check base warranty separately from mattress warranty

A note on our range: our current Koala bed base line-up (Kirribilli, Balmain, Paddington, Brunswick, Joey) is a range of premium timber fixed bases, which suit the different-firmness split king setup rather than the independent-adjustable setup. If you're prioritising the adjustable-base benefit specifically, our King Single mattresses can be paired with a third-party adjustable base sized for a split king pairing.

Build Your Split King with Our Mattress Range

Our Koala mattress range is available in King Single sizes across all 5 models, so you can pair two matching mattresses or two different firmnesses to build your split king. All feature Kloudcell® comfort, Zero Disturbance® technology, CertiPUR-US® certified foam, our 120-night trial and 10-year warranty. Popular split king pairings:

• Koala Mattress × 2 (Firm/Medium-Firm flippable): the original for couples who agree on firmness; each partner can independently flip their side of the mattress between Firm and Medium-Firm. 25 cm total height with 7 cm Kloudcell® (40% more than SE) and zip-off topper with carbon-zero TENCEL™ Lyocell ticking.

• Koala Plus Mattress × 2 (Medium-Firm/Medium flippable): for couples wanting Cooling Gel Kloudcell® and seasonal adaptability. 28 cm total height with 8 cm Kloudcell® (60% more) and reversible summer/winter topper (CoolThread™ / Organic Cotton).

• Mix-and-match pairings: pair a firmer model on one side (Koala Mattress) with a plusher model on the other (Koala Luxe) to solve genuinely-different-firmness-need couples.

Browse our king single mattresses for split king pairings, our king mattresses if you'd prefer a standard single-mattress king, our wooden bed base and frames for a matching fixed base, or our full premium mattress range.