An Alaskan king mattress is the largest bed size most people will ever encounter — roughly 108 by 108 inches, or about 9 feet by 9 feet, which is wider than a standard king is long. In 2026 there’s still no single universal manufacturing standard for this size, which means shopping for one requires understanding two very different paths: a true custom one-piece mattress, or two twin XL mattresses joined together.
The Best Alaskan King Mattress Options at a Glance
Zinus Joined Two Twin XL to King Conversion Kit + Mattresses
- Dramatically cheaper than a true custom Alaskan king
- Each twin XL can have different firmness for co-sleeping partners
- Easier to move and replace one half if needed
- A center seam is still noticeable underfoot and between sleepers
- Requires a custom or joined bed frame to keep both halves aligned
Brooklyn Bedding Custom Alaskan King Mattress
- True one-piece construction with no center seam
- Hybrid support holds up well across a very large surface
- Custom firmness options at order time
- Significant lead time since it's built to order
- Price and weight make returns or exchanges impractical
Nolah Custom Alaskan King Hybrid Mattress
- Cooling gel foam layer performs well even at this size
- Motion isolation is strong for a mattress this large
- Custom order allows firmness selection per side
- Among the more expensive custom options available
- Long production and delivery timeline
Instant Comfort Twin XL Zippered Mattress Connector
- Very affordable way to test the joined-mattress approach
- Works with most standard twin XL mattresses
- Easy to remove if you change your mind later
- Doesn't fully eliminate the gap or seam between mattresses
- Only as good as the two mattresses it's connecting
Saatva Custom Alaskan King Mattress
- Traditional innerspring feel with better edge support
- Built as a genuine one-piece custom mattress
- White-glove delivery included given the size and weight
- Among the priciest options in this category
- Heavier construction makes future moving a real project
Custom One-Piece vs Joined Twin XL: The Real Decision
This is the single most important choice to make before shopping. A true custom Alaskan king is manufactured as one continuous mattress with no seam, giving the most consistent sleep surface but coming at a significant price premium and long production lead time — often 4-8 weeks. Joining two twin XL mattresses with a connector kit is dramatically cheaper and lets each side have different firmness, which is genuinely useful for couples or families with different preferences, but there will always be a slight seam or ridge where the two mattresses meet, even with a good connector and topper.
Why Alaskan Kings Exist
This size isn’t a mainstream mattress industry standard — it’s a workaround that emerged from co-sleeping families, especially those with young kids or multiple pets who all end up in the same bed, and from couples who each want the personal space of a queen without sleeping in separate rooms. Because it’s non-standard, sheets, frames, and bedding all need to be custom-ordered or DIY-assembled alongside the mattress itself.
Frame and Room Requirements
A 9×9 mattress needs a genuinely large bedroom — leave at least 2-3 feet of clearance on all sides for walking space, which means the room itself should be at least 13×13 feet to feel comfortable rather than cramped. Bed frames for this size are almost always custom-built or assembled from two connected king/queen frame units, since standard frame manufacturers don’t produce Alaskan king frames as a stock item.
Sheets and Bedding
Standard king sheets will not fit an Alaskan king mattress — you’ll need custom or specialty oversized bedding, which is a smaller market with fewer options and higher prices. Some buyers use two king-size flat sheets or have bedding custom-sewn. Factor this ongoing cost into the decision, since replacing sheets, mattress protectors, and comforters at this size is meaningfully more expensive than standard king bedding for the life of the mattress.
| Option | Construction | Seam | Lead Time | Price |
|---|---|---|---|---|
| Zinus Joined Twin XL | Two mattresses + connector | Yes, noticeable | Standard shipping | $$ |
| Brooklyn Bedding Custom | True one-piece hybrid | None | 4-8 weeks | $$$$ |
| Nolah Custom Hybrid | True one-piece hybrid | None | 4-8 weeks | $$$$ |
| Instant Comfort Connector | Accessory only | Yes | Standard shipping | $ |
| Saatva Custom | True one-piece innerspring | None | 4-6 weeks | $$$$ |
Weight Capacity and Delivery
A true one-piece Alaskan king mattress can weigh 300-400+ lbs, which means white-glove delivery (where the company brings it inside and sets it up) is essentially mandatory rather than optional — factor this into the total cost even if it’s advertised as included. Weight capacity for sleeping is generally rated per-side rather than as one combined number, since the whole point of this size is accommodating multiple sleepers with independent support zones.
Mistakes to Avoid
- Assuming standard king bedding will work with minor adjustment. It won’t — budget for genuinely custom or specialty sheets from day one.
- Underestimating room size needs. A 9×9 mattress needs a large bedroom with real walking clearance, not just floor space equal to the mattress itself.
- Choosing joined twin XLs without a proper connector kit. Simply pushing two mattresses together without a strap/zipper system creates a gap that gets worse over time.
- Not confirming delivery logistics upfront. Doorways, stairwells, and elevators can all become problems with a mattress this large — confirm delivery access before ordering.
If a full Alaskan king feels like more bed than you need, our guides to mattresses under $500 and cooling mattresses for hot sleepers cover more standard sizes at a fraction of the cost. For frame options at this scale, browse bed frames, and check our bed sizes and dimensions guide for how Alaskan king compares to standard king and California king. The full mattresses hub has more sizing options if you’re still deciding.
Our Top Alaskan King Pick
Brooklyn Bedding's custom Alaskan king delivers a true seamless 9x9 sleeping surface.
Check price on AmazonWhat are the exact dimensions of an Alaskan king mattress?
An Alaskan king mattress is typically 108 inches by 108 inches, roughly 9 feet by 9 feet, though exact dimensions can vary slightly by manufacturer since there’s no strict industry standard for this size.
Is it cheaper to join two twin XL mattresses than buy a custom Alaskan king?
Yes, significantly. Joining two twin XL mattresses with a connector kit typically costs a fraction of a true one-piece custom Alaskan king, though it comes with a noticeable seam where the two mattresses meet.
What size room do I need for an Alaskan king bed?
Plan for a bedroom of at least 13×13 feet to leave 2-3 feet of walking clearance on all sides of the mattress. Smaller rooms will feel cramped with a bed this large.
Do standard king sheets fit an Alaskan king mattress?
No, standard king sheets are too small. You’ll need custom-sized or specialty oversized bedding, which is a smaller market with higher prices than standard king sheet sets.
How long does it take to receive a custom Alaskan king mattress?
Most true custom one-piece Alaskan king mattresses take 4-8 weeks to manufacture and ship, since they’re built to order rather than kept in standard inventory.
Can each side of an Alaskan king mattress have different firmness?
Yes, this is one of the main advantages of the joined twin XL approach — each twin XL mattress can be a different firmness level, which is harder to achieve with a true one-piece custom mattress.
How much does an Alaskan king mattress weigh?
A true one-piece Alaskan king mattress can weigh 300 to 400+ pounds, which is why white-glove delivery service is essentially required rather than optional.
Why don’t more furniture stores carry Alaskan king mattresses and frames?
Alaskan king isn’t a recognized mainstream mattress industry size, so demand is low relative to standard sizes, meaning most retailers only offer it as a custom or special-order item rather than in-stock inventory.
Marcus Reed
Marcus Reed is TalkBeds' Senior Mattress Tester and the person behind most of the hands-on verdicts you'll read on the site. Over more than eight years reviewing beds, he has personally tested 200-plus mattresses across every major category, from budget boxed foam… Full profile & sources →