Alaska King Bed: How to Build the Biggest Bed in America (And What to Buy)

If you’ve stumbled onto the term “Alaska king bed” and assumed it was a myth or a marketing gimmick, you’re not alone — it’s one of the most searched-for oversized bed sizes on the internet, and yet almost no mattress store actually stocks one. In 2026, the Alaska king remains a real, buildable bed size rather than a manufactured product line, and that changes how you need to shop for it. This guide breaks down exactly what an Alaska king is, how it compares to other jumbo sizes, and which frames, connectors, and bases actually make one work in a real bedroom.

What Is an Alaska King Bed, Exactly?

An Alaska king bed measures roughly 108 inches by 108 inches — a perfect 9-foot square. It’s not manufactured as a single mattress by any major brand; instead, it’s created by pushing two California king mattresses (72″ x 84″ each) side by side, which gets you close to 144″ x 84″, then it’s typically customized further, or built from two extra-long custom mattresses sewn or strapped together to hit the full 9×9 footprint. Some specialty mattress makers will sew two Cal kings into one continuous cover, but the vast majority of Alaska king setups we’ve come across are DIY builds using two separate mattresses on two joined frames.

The name is regional folklore more than official terminology — it supposedly originated from oversized custom beds built for large Alaskan homes and lodges where two people (or a whole family) needed serious real estate to spread out. Whatever the origin, the appeal is obvious: this is the largest bed size most people will ever consider putting in a house.

Alaska King vs. Other Oversized Bed Sizes

As you can see, the jump from California king to Alaska king isn’t incremental — it roughly doubles your sleeping surface. That’s a huge draw for parents who co-sleep with toddlers, couples who share the bed with large dogs, or anyone who simply wants to never touch their partner accidentally in the middle of the night.

How to Build an Alaska King Bed at Home

Step 1: Choose Your Mattress Combination

Most people combine two California king mattresses. It’s the closest standard size to a true 108″ x 108″ footprint once you account for a small gap, and Cal king mattresses are widely available compared to trying to source two custom 9-foot mattresses. Some builders instead combine a king and a California king, but this creates a noticeable height and size mismatch that’s harder to disguise.

Step 2: Pick Two Compatible Frames

Buy two identical frames whenever possible. Mismatched frame heights are the single biggest reason Alaska king builds feel unstable or look sloppy. Platform frames without protruding side rails (like the Zinus Suzanne or Molblly options above) push together with the smallest possible gap, which matters once you’re trying to bridge the mattresses on top.

Step 3: Bridge the Gap

Even with the best frames, you’ll get a seam where the two mattresses meet. A bed bridge or mattress connector fills that dip so you’re not rolling into a valley in the middle of the night. This is genuinely the piece people skip and then regret — we’d call it non-negotiable for anyone actually sleeping across the seam rather than keeping to one half.

Step 4: Secure Everything

Use a king or Cal king-sized fitted sheet set designed for oversized combinations, or have a custom sheet made — standard sheets won’t stretch across a 108″ span. Non-slip pads under each frame’s legs also help prevent the two halves from slowly drifting apart over months of use.

Room Size and Space Planning

A 9-foot by 9-foot mattress alone needs a bedroom with at least 12 to 13 feet of usable width and depth once you account for walking space, nightstands, and dresser clearance. We’d recommend measuring your room’s actual clear floor space before committing — an Alaska king in a room that’s too tight will make the space feel like a hotel storage closet rather than a primary suite. If your room can’t comfortably fit one, a Wyoming king (84″ x 84″) is a solid middle-ground alternative that still delivers noticeably more space than a standard California king without demanding a dedicated large room.

Budget Breakdown

Because you’re essentially buying two of everything, budget realistically. Two mid-range platform frames typically run $300–$600 combined, a bed bridge connector adds $30–$80, and two Cal king mattresses can range from $1,200 to well over $4,000 depending on materials. All-in, most Alaska king builds land somewhere between $2,000 and $6,000 before bedding, which is worth planning for since this isn’t a size you’ll find bundled as a single purchase anywhere.

Frame Considerations Specific to Alaska King Builds

• Matching leg height: Even a half-inch difference between two frames creates a visible and physical dip at the seam.
• Weight capacity: You’re supporting two mattresses and likely two or more sleepers plus pets — heavier-duty steel frames with more legs distribute that load far better than basic wood frames.
• Slat spacing: Tight slat spacing (under 3 inches) supports memory foam and hybrid mattresses without sagging, which matters more at this scale since there’s more unsupported surface area overall.
• Headboard continuity: A single continuous headboard, or two headboards that visually match, goes a long way toward making the finished bed look like one cohesive piece rather than two twin setups pushed together.

Related buying guides

• Browse all bed guides
• Best platform bed frames
• Bed frames with storage
• Mattress buying guides
• Adjustable bed bases
• Bed sizes and dimensions guide
• Cooling mattresses for hot sleepers

Written by

Sophie Laurent

Beds & Bedroom Editor

Sophie Laurent is TalkBeds' Beds & Bedroom Editor. With more than ten years covering home and furniture, she leads everything on the site that isn't the mattress itself: bed frames, platform beds, headboards, bunk and kids' beds, sizing, and the interiors decisions… Full profile & sources →