King Size Mattresses

Go big and sleep comfortably with Serta’s selection of King-size mattresses. With enough room for couples or anyone who wants a wider sleep surface, a King mattress is optimal for master or large bedrooms.

Why You Should Choose a King Size Mattress

When compared to the California King, the King size mattress is the more popular choice out of the two largest mattress sizes. It is ideal for couples who want plenty of space to sleep comfortably or have human or fur babies that crawl into bed with them. A King mattress also provides ample space for single sleepers who want the luxury of extra room to move around during the night. It is approximately 16 inches wider than the most popular mattress size, a Queen. If you have a big bedroom and enjoy sprawling out and getting comfy, you might want to consider going with a King size bed.


Still not convinced a King is best for you? Check out some of our frequently asked questions below.


What size is a King size mattress?

Approx. Dimensions: 76” X 79.5” / 6,042 sq in / 42 sq ft


A King-size mattress is the widest offering at 76 inches. A Queen is 60 inches wide and a California King is 72 inches wide.


King vs California King. What's the difference between the two?

The measurements of a regular King are approximately 76 inches in width and 79.5 inches in length. The measurements of a California King are a bit longer and not as wide, the dimensions are approximately 72 inches wide by 83.5 inches long.


King Size Mattress Dimensions: 76″ Wide x 79.5″ Long

California King Size Mattress Dimensions: 72″ Wide x 83.5″ Long


Read more about the King vs California King differences, here.


Do two Twins make a King?

Actually, no they don’t. Two Twins put together fall approximately 5 inches short, but two Twin XLs put together are the same dimensions as a King.


What is a Split King?

A Split King is made up of two Twin XL mattresses and measures the same as a standard King size but are generally bought for split adjustable bed frames or couples who have different sleep preferences and would like two different types of mattresses.


How much is a good King size mattress going to cost?

A good King on average can range anywhere from $800 upwards to $5,000 depending on the features and materials used to make the mattress.


Should I buy a King sized mattress in-store or online?

It’s all about your own personal shopping preference. Some people are online shoppers and that is what they are most comfortable with while others are more of an in-person shopper where touching, feeling and seeing the product is the only way they want to shop. So it really is all about which way you prefer to shop. There really is no right or wrong way to shop for a mattress. If you are, however, the latter, click here to find a Serta store near you.


Does Serta offer any customization options on King mattresses?

From innerspring to memory foam to mattress-in-a-box to hybrid mattresses, Serta offers different models that are available in King. Most mattresses have different cooling and firmness level options. So no matter your sleep preference and preferred sleeping position, back, stomach and side sleepers alike, Serta has a mattress model that will be perfect for you.

Can I expedite my order?

We do not have an expedited delivery option at this time. Our site will provide the best delivery estimate at checkout.

Do you ship internationally?

Directly on our website, we only ship within the United States, to the lower 48 states. At this time we do not offer shipping to Alaska or Hawaii.

Do you offer financing?

Financing is available directly through our website. We have partnered with Affirm to offer financing or pay-over-time options for our customers. At checkout, you will be given the option to pay through Affirm. If approved, you will be given loan options for 3, 6, or 12 months. All interest is provided up front, there are no hidden fees, and only a soft credit check is done through Affirm's system for approval. After you've confirmed your choice, you will be redirected back to our website to complete checkout.

Affirm only requests a soft credit check for approval, so the credit inquiry won’t affect your credit score. Once you've selected your financing term, you will be redirected back to the website to complete your purchase.

For returns and cancellations, refunds will be processed through Affirm and posted to your Affirm account. Refunds will be processed within 3-10 business days. Keep in mind the interest charge will not be refunded.

Please note that financing through Affirm is not available in West Virginia and Iowa.

What is the difference between ordering from and another retailer?

When you place an order through, you are backed by the 120-Day In-Home Trial. We know ordering a mattress online can be intimidating, so we want to take the risk out of it for you with the in-home trial that allows the perfect amount of time to test the mattress and accessories in your home and make sure it's right for you. If you decide it is not the right fit, we make returns easy and free.

Serta products are sold at many different retailers through the United States. Our goal is to be able to serve our sleepers where they feel the most confident purchasing their Serta products. Many retailers will have products on display for sleepers to test out before making your decision, and may offer different pricing or promotional advantages for buying directly through a retailer. Retailers may also have different models than what you see directly on the website.

Regardless of where you purchase, you can be confident you are getting a quality Serta product.

Do you make custom sizes?

We are unable to provide custom sizes at this time. For now, we carry industry standard sizes of twin, twin XL, full, queen, king, and California king.

Why buy Serta online?

120-Day In-Home Trial

Experience the mattress in your home for up to 120 days. If you’re not completely satisfied, you can exchange or return it for a refund.

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You should be able to rely on the quality of your rest night after night. That’s why every Serta® mattress is backed by Serta’s 10-year limited warranty.

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Free Shipping & Returns

All mattresses and foundations ship free and feature free returns when you order directly from

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All Serta mattresses are designed and assembled in the USA, leveraging our 85 years of manufacturing expertise.

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certipur-us® certified

Rest easy knowing Serta uses only CertiPUR-US® Certified Polyurethane Foam.

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Family, woman on the left, young son in the middle and man on the right laying on a mattress asleep

Try in stores

Want to test our products before you buy? Our Sleep Ambassadors will offer you a personalized, no-pressure in-store experience. Don't live near a Serta shop? Learn where else you can find us!

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