by A split king is two twin XL mattresses side by side (38" x 80" each) that together match the 76" x 80" footprint of a standard king. Choose a split king if you and your partner want different firmness levels or if you plan to use an adjustable base independently. Choose a standard king if you share the same sleep preferences and want a single uninterrupted sleep surface. Our top mattress for either configuration is the Saatva Classic, which ships in both king and split king sizes with free white-glove delivery.
Saatva Classic
9.2/10
- Available in king and split king (two twin XLs) with the same luxury build
- Three firmness options let each partner pick Plush Soft, Luxury Firm, or Firm in a split configuration
- Free white-glove delivery, in-room setup, and old mattress removal
- Dual-coil construction runs cooler than most foam beds
- 365-night trial and lifetime warranty
- Split king means two separate mattresses, so a mattress bridge or connector is needed to minimize the gap
- $99 return fee applies during the trial
- Ships uncompressed, so it needs room for delivery
The Saatva Classic is the most practical choice for couples who want both options open: order two twin XLs in different firmness levels for a split king, or a single king for a unified surface. White-glove delivery makes the split king setup less of a logistical headache.
Split king vs king: the exact dimensions
| Configuration | Total Width | Total Length | Components | Gap |
|---|---|---|---|---|
| Standard King | 76" | 80" | 1 mattress | None |
| Split King | 76" (38" + 38") | 80" | 2 twin XL mattresses | Small center gap |
Both configurations use the same frame footprint. A split king requires a king-size adjustable base or bed frame that can accommodate two twin XL mattresses. The footprint of the room, the bed frame, and all bedding (sheets, comforters) remain the same size.
Who should choose a split king
A split king setup makes sense in three specific situations:
- Different firmness preferences: One partner needs firm support for back pain, the other wants plush pressure relief for hip or shoulder pain. A split king lets each person choose independently.
- Adjustable base users: Split king adjustable bases let each side raise or lower independently. One partner can elevate the head for reading or reflux without disturbing the other.
- Significant weight difference: When one partner weighs considerably more, the ideal firmness for each person may differ by two or three firmness levels. Separate mattresses solve this cleanly.
The practical cost is the center gap. Most split king owners use a mattress gap filler or mattress connector strap to reduce the seam, but it never completely disappears. For couples who sleep close together at the center, this can be noticeable.
Who should choose a standard king
If you and your partner prefer the same firmness level, a standard king is simpler, cheaper per mattress, and provides an uninterrupted sleep surface. There is no center gap, no need for a split-compatible adjustable base, and a wider selection of mattresses to choose from since not all brands offer twin XL in the same models.
A standard king also works better for couples who share the center of the bed regularly, have children or pets who join them at night, or are buying into a simpler bedding setup.
Amerisleep AS3
9.0/10
- HIVE 5-zone layer adapts to different body zones for both partners on a shared surface
- Plant-based Bio-Pur foam relieves pressure and runs cooler than standard memory foam
- Excellent motion isolation, so one partner moving does not wake the other
- CertiPUR-US certified, made in the USA
- Available only as a single mattress, so no split firmness option
- Edges are softer than a coil hybrid
- Sleepers over 230 lb may prefer the firmer AS5 Hybrid
For couples who agree on medium firmness, the AS3 in king size eliminates the motion transfer problem and delivers strong pressure relief across both sides of the bed with no center gap.
Adjustable base compatibility
The biggest practical advantage of a split king is adjustable base compatibility. A split king adjustable base raises or lowers each side independently. Practically, this means one partner can use zero-gravity or anti-snore positioning without forcing the other into the same angle.
Standard king adjustable bases exist, but they raise and lower both sides together. If individual positioning matters, split king is the only way to achieve it without two separate beds.
If you are considering a split king primarily for adjustable base use, look for mattresses specifically designed for flex compatibility, usually foam or pocketed coil. Most innerspring mattresses are not recommended on adjustable bases because the rigid coil grid can crack under repeated flex, though some premium models like the Saatva Solaire are purpose-built for it.
Cost comparison
A split king typically costs more than a standard king because you are buying two twin XL mattresses. The price per twin XL is usually higher than half the king price because smaller sizes often have lower per-unit discounts. Expect to pay 15 to 25 percent more for a comparable split king setup than a single king.
| Item | Standard King | Split King |
|---|---|---|
| Mattress cost | 1x king price | 2x twin XL price (typically higher total) |
| Sheets/bedding | Standard king sheets | Standard king sheets (same size) |
| Bed frame | Standard king frame | Split-king-compatible frame or adjustable base |
| Gap filler | Not needed | Recommended ($20-60) |
Bedding for a split king
The outer dimensions of a split king match a standard king, so king sheets, comforters, and duvet covers fit both configurations. The difference is that a split king tends to move more during the night because the two mattresses can shift slightly relative to each other. Using a mattress connector strap or a non-slip mattress pad under each twin XL limits this.
Some couples use two twin XL comforters instead of one king comforter to avoid blanket-stealing. Two twin XL comforters side by side cover the same area as a king comforter and move independently with each person.
Choose a split king if you need different firmness levels or plan to use independent adjustable base positioning. Choose a standard king if you share preferences and want a simpler, seamless setup. The Saatva Classic handles both configurations with a luxury build and free white-glove delivery.
Frequently asked questions
Can you use regular king sheets on a split king?
Yes. The outer dimensions of a split king (76" x 80") match a standard king, so standard king sheets fit. The fit is the same, though the two mattresses may shift slightly under the sheets over time.
Is a split king the same as two twin XLs?
Exactly. A split king is two twin XL mattresses placed side by side on a king-size frame. Each twin XL measures 38" x 80", so two together produce the 76" x 80" king footprint.
Do split king mattresses have a gap in the middle?
Yes. Because two separate mattresses sit next to each other, there is a small center gap. A mattress gap filler or connector strap minimizes but does not fully eliminate it. Most couples who sleep toward their own side find it unnoticeable.
Can you put different firmness mattresses in a split king?
That is the primary reason to choose a split king. Each twin XL can be a different firmness level or even a different mattress model entirely. Brands like Saatva, Amerisleep, and Purple all offer twin XL sizes that can be mixed.
What is the difference between a split king and a dual king?
The terms are used interchangeably. Both refer to two twin XL mattresses side by side filling a king frame footprint. Some brands use "dual king" in their marketing while retailers use "split king" more commonly.