When you’re shopping for a premium mattress, selecting the right size is just as important as choosing the right material, support level, and comfort profile. Two of the largest “standard” mattress sizes available are the King and the California King — but despite both having “King” in their name, they’re not the same. Below you’ll find an in-depth comparison of the two — their dimensions, advantages, and trade-offs.
Dimensions
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A standard King mattress (also sometimes called an “Eastern King”) typically measures 76 inches wide × 80 inches long. Serta+2Casper Sleep+2
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A California King mattress (sometimes “Western King”) typically measures 72 inches wide × 84 inches long. Casper Sleep+2Sleep Foundation+2
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In terms of surface area: the King is about 6,080 square inches, whereas the Cal King is about 6,048 square inches. Purple+1
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In plain terms: the King gives you more width, the California King gives you more length. Sleep Foundation+1
What this means in practice
Because of the difference in shape, the implications for how you sleep, how your room fits the bed, and how you use the space can vary:
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Room shape & size: If your bedroom is wide, or roughly square (say 12’×12’ or larger), the extra width of a King makes more sense. A California King, being narrower but longer, fits better in a room that is long and narrow (for example a 11’×13’ or 12’×14’ space) because it won’t dominate the width as much. Purple+1
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Height of sleepers: If you or your partner is especially tall (for example 6′3″+), the extra 4 inches of length offered by the California King may be beneficial (so your feet don’t hang off). Meanwhile, if you’re of more typical height, the extra width of the King may feel more spacious. Each Night
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Sharing the bed (couples, pets, kids): If you share your bed with a partner, children, or pets, the King’s extra width can give more “elbow room” side-to-side. For example, two adults + a pet might feel less crowded on a King. On the other hand, if legroom is more of a limiting factor than width, the Cal King may be the winner. Casper Sleep+1
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Bedding, frames, accessories: Because the King size is more common, it tends to be easier (and often cheaper) to find matching sheets, frames, adjustable bases, and mattress toppers. The California King may sometimes require more careful sourcing of accessories. Casper Sleep
Pros & Cons Summary
King mattress (76×80):
Pros
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Widest standard mattress — lots of lateral space.
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Great for couples, lots of motion freedom, easier if children or pets jump in.
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Easier to find bedding and accessories.
Cons -
If you’re very tall, the length might be limiting (80″ might not be enough).
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In a narrower room, the width may make the space feel crowded.
California King (72×84):
Pros
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Extra length is great for tall sleepers.
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Because it’s narrower, it may fit better in long/narrow bedrooms.
Cons -
Slightly less total surface area (though marginal).
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Less width means less side-to-side space.
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Accessories may be less common / a bit more expensive.
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If you’re under 6′2″ and the room is wide, you might prefer the width of the King.
How to decide
Here are some questions that can help you pick:
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How tall are you (and your partner)? If one or both of you are very tall, lean toward California King.
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How big is your room? Get exact measurements of your bedroom including clearance for walking around the bed.
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Do you share with kids or pets and want wide room to spread out? If yes, King may be more suitable.
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How available are frames, sheets, and other accessories in your region, and are you willing to hunt for less-common sizes?
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What feels more comfortable to you: width or length? If you tend to sleep diagonally or sprawl side to side, width might matter more; if you sleep straight and your feet often hit the end, length might matter more.
