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Cal-King size starting at $1199 
Available in 5 models
Cal King Size Mattress

A high-quality California King mattress for everyone

Enjoy unbeatable comfort and the ultimate sleep experience.

Amerisleep - California King Size Mattress

Sleep/comfort fit for a king

Business Insider called the AS2 the “best mattress for back pain.” Similar to the AS1 but with one additional inch of Bio-Pur®, this mattress will give back and stomach sleepers all the cushioning they need.

Cal King starting at $1849

Shop the AS2
A mattress surpassing all expectations

Amerisleep’s best-selling mattress thanks to its medium feel, which gives the bed an even balance of support and comfort for every type of sleeper. Allure even calls it one of the best mattresses you can buy online.

Cal King starting at $2049

Shop the AS3
A mattress surpassing all expectations

Amerisleep’s best-selling mattress thanks to its medium feel, which gives the bed an even balance of support and comfort for every type of sleeper. Allure even calls it one of the best mattresses you can buy online.

Cal King starting at $2049

Shop the AS3
Sleep/comfort fit for a king

Business Insider called the AS2 the “best mattress for back pain.” Similar to the AS1 but with one additional inch of Bio-Pur®, this mattress will give back and stomach sleepers all the cushioning they need.

Cal King starting at $1849

Shop the AS2
King-size comfort for a better night’s sleep

The AS5 is our softest mattress and the only model in Amerisleep’s lineup with the Active Flex layer, which allows us to create the softest mattress possible, without making you feel stuck as you move around at night.

Cal King starting at $2649

Shop the AS5
Best firm mattress

The AS1 is Amerisleep’s firmest mattress. It’s perfect for back and stomach sleepers who are looking for very little give— but don’t worry, this bed still contains one inch of Amerisleep’s soft, pressure-relieving Bio-Pur®.

Cal King starting at $1649

Shop the AS1
Best soft mattress

The AS4 is medium-soft, so it’s a great fit for side or combo-sleepers who need slightly more cushioning than the AS3 provides. While it’s softer than the AS3, it still has plenty of support for your back, spine, and hips.

Cal King starting at $2049

Shop the AS4

Comfortable, pressure-relieving sleep each night.

The combined effects of plant-based Bio-Pur® and supportive HIVE® technology ensure a cool, restful sleep no matter your body type. Bio-Pur® responds quickly, so sleepers never feel “stuck.”

Supportive king size mattress

A good night’s rest shouldn’t be the exception.

Amerisleep mattresses are made with every sleeping position in mind. Sleepers will wake feeling refreshed and ready for the day, thanks to high-quality Bio-Pur®, a plant-based memory foam that cushions heavier parts of the body for optimal pressure relief.

Comfortable king size mattress
Sleep soundly every night on the perfect mattress for you. Shop Our Mattresses

Are California King mattresses good for everyone?

California King beds work well for taller couples or anyone with extra bedroom space.

Abundant sleeping room:

California King beds are the longest mattress available, so you can move around as much as you want.

Perfect for couples:

California King mattresses are one step above a standard king. The extra 4 inches of length (84 inches total) will give you all the room you need.

Fit for a king-size room

California King mattresses are the perfect size for most master bedrooms.

How much will I be spending on my new California king size mattress?

Setting reasonable expectations with your current budget can help you find a high-quality mattress.

You don’t need to throw down a bunch of money to get a nice bed. Many mattress brands tout extravagant features with their beds, but most of the time those features are just a marketing tactic.

The average mattress model starts off with a basic rate, and the price increase depends on special materials or features such as cooling foam or wrapped coils.

High quality king size mattress detail

Common mattress features increasing mattress cost

  • Cooling technologies, like plant-based foam, gel foam, or copper-infused foam
  • Specialty foams and technologies from specific brands
  • Edge support from poly-foam edging and innerspring coils
  • Euro-style pillow top made from high-quality materials
  • A warranty longer than 10 years
  • Soft, thick comfort foams (more layers, more expense)
  • All-natural materials like organic cotton, plant-based foams, and natural latex

How big is a California King size mattress?

A king size mattress is 80 inches long and 76 inches wide.

  • Twin
    38" x 75"
  • Twin XL
    38" x 80"
  • Full
    53" x 75"
  • Queen
    60" x 80"
  • King
    76" x 80"
  • Cal King
    72" x 84"
  • Split King
    38" x 80"(x2)

Which mattress size is best for me?

  • Twin - 38" x 75"

    Kid's room, studio apartments
  • Twin XL - 38" x 80"

    College dorm, studio apartments
  • Full - 53" x 75"

    Kid's room, studio apartments
  • Queen - 60" x 80"

    Master bedrooms, guest rooms
  • King - 76" x 80"

    Extra large master bedrooms
  • Cal King - 72" x 84"

    Extra large master bedrooms (10' x 12')
  • Split King - 38" x 80" (x2)

    Master bedrooms, adjustable beds

Shop Amerisleep mattresses and save

California King size starting at $1199 with promo

Shop Now

Shop Amerisleep mattresses and save

California King size starting at $1199 with promo

Shop Now

Is it possible to find a high-quality bed in a box mattress on a budget?

The average queen-size mattress costs around $1000-2000. Yes, even on a budget, you can get high-quality foams along with soft and breathable textiles. Bed in a box brands sell their beds directly to the customer, and the mattress arrives directly at your door for convenient transfer. No need to borrow a friend’s truck and transport the mattress from the store to your home.

If you’re still unsure if beds that come shipped in box are worth the money, try one out using their sleep trials or go visit one of their showrooms.

twin size mattress shipping box

How are Amerisleep mattresses different
than traditional memory foam mattresses?

Memory foam, also known as viscoelastic foam, is popular because it relieves pressure while still bouncing back quickly enough to be supportive. Because of its density, memory foam tends to trap heat. Amerisleep offsets this problem by using plant-based Bio-Pur®.

Made with castor oil instead of petrochemicals, it releases minimal off-gassing odors upon opening and circulates air easier than traditional memory foam.

Amerisleep vs. Other Mattress Types

Breaking down each layer of the AS3,
Amerisleep’s most popular mattress:

Thanks to the premium quality materials in each of our mattresses, you can sleep comfortably for years to come.

  • 1

    Stretchy, soft cover ensures the top layer stays cool.

  • 2

    Plant-based Bio-Pur® hugs your body and bounces back to its original shape quickly.

  • 3

    The Affinity Layer with HIVE® offers pressure relief and enhanced lumbar support.

  • 4

    The durable Bio-Core® base layer distributes your weight evenly across the sleep surface, ensuring the mattress lasts for the entire length of the warranty.

twin size mattress layers

See why our customers love to snooze and tell

We absolutely love our AS3! We both had back pains prior to purchasing this bed and can honestly say, after 4 months, we haven't noticed a single ache or pain since. Would purchase again and again!

Lake Charles, LA

I purchased the AS3 mattress 3 months ago, and it has been a lifesaver. My husband and I have back issues, and we needed a bed that would help us get quality sleep. We have always struggled with being able to sleep through the night due to aches and pains and now that we have been sleeping on our AS3 mattress for 3 months now, we finally are able to sleep comfortably through the ENTIRE night!

Sioux Falls, SD

I purchased the AS3 and couldn't be happier, I now own 2! A king size and a king size and I will never buy another brand again. I would definitely recommend the king size AS3 over and over again, if you're considering buying this mattress because you're not getting great sleep or you're simply due for a new mattress... TREAT YOURSELF. I promise you will not regret it.

Westchester County, NY

We've slept on this bed for 9 months now. It's the perfect blend of softness and support. It's so comfortable we have accidentally slept till noon on many occasions! My husband has had knee and shoulder surgery and this bed is comfortable for him to sleep on his side. My back and hip pain from standing at work all day is decreased. My kids are always trying to sneak in to sleep on it. This is the best bed we've ever owned.


We have had our Amerisleep AS4 for about two months now. It is living up to the hype so far. My husband and I both have back problems and needed support plus give in the mattress. The Amerisleep AS4 fits our needs perfectly (for reference purposes, my husband and I are both under 160lbs). In fact, the first night we had our new Amerisleep, my husband slept for 10 hours straight! That has never happened in the 20+ years we've been married!


Love the mattress! I have back problems and this mattress is so comfortable. I sleep better and the usual soreness I felt every morning with my previous mattresses has disappeared. We liked the first mattress so much, we bought another for the guest room.

Dothan, Alabama

I was skeptical of ordering a mattress online even though I was able to test it in the store prior to ordering. The delivery was a breeze and the mattress didn't even need to off-gas, but it's the sound sleep provided that is the point of this review. I sleep on my back now and haven't in years. Who knew I was a back sleeper? This mattress (A2) is firm and supportive yet still soft and cozy and has provided the best sleep I've ever had. Thanks for making me excited about bed again!

Portland, OR

This is an excellent mattress. I was a bit worried about getting the AS2, as I am primarily a side sleeper, but I am getting the best sleep of my life whether I am on my side or my back. The best part is how sturdy yet quiet the bed is. My partner and I go to sleep and wake up at different times, and neither of us notice when the other gets in/out of bed. I also run pretty hot, and in my previous bed was no stranger to waking up sweaty, but this mattress keeps me cool and dry.


We are both back and side sleepers and the mattress works great for us. This mattress made sleeping with a bad hip before and after hip replacement surgery possible. Our old mattress made sleeping especially on the side intolerable.

Murrieta, CA

I have always had back issues waking up and difficulties getting to sleep on my current mattress and previous ones but when my new mattress was delivered I noticed a difference the first night! I now look forward to using it and sleep like a rock.

Atlanta, GA

This is my first memory foam mattress. I have always had a pillow top. I was afraid to order the wrong type for my body/sleep type. I spoke with customer service and was recommended the AS5 since birth my husband and I are smaller people (I'm 112 pounds and 5'2 and my husband is 5'8 and 165 pounds), and we both are side sleepers primarily (I also sleep on my back). I was worried it would be too soft or not soft enough, but it is perfect.

Pittsburgh, PA

I like a firm mattress and shopped in stores for months trying to find the right one for me. None were comfortable. I took a shot with the Amerisleep AS1 after many reviews said it was a firm mattress. Best decision! It was so comfortable that I turned around and bought one for my daughters full size bed.

Fayetteville, AR

My wife has a bad back so we needed a very firm mattress. Our old mattress was sagging and had to go so we bought a very nice split king mattress but it was just not firm enough. We saw Amerisleep and took a chance. No more back pain - we are amazed but love it. Would highly recommend.

Walker, TX

My wife and I use this bed every single night now. We chose the firm model in hopes we would wake up with less aches and pains after a night of sleep. It’s done that and more! Super comfortable bed while being extremely sturdy. Can’t believe how easy and fast the purchasing process was either. I would highly recommend this bed to anyone and everyone. What are you waiting for??


Frequently Asked Questions

What is the difference between a king size and a California king size mattress?

A king-size bed is wider and shorter, measuring at 76” by 80”, while a California king size mattress is longer and more narrow at 72” by 84”.

Why is it called a “California king”?

Also known as a “western king” California king size mattresses were created in California to accommodate larger living areas, and have since grown in popularity.

Which one is better, Cal king or king?

It depends on what you value more—length or width. California king size mattresses are better-suited for sleepers over 6-feet-tall who need the additional legroom. Standard king mattresses are best for couples who prefer extra personal space to get comfortable.

What is the best California king size mattress?

The best California king size mattress should relieve pressure points, especially in heavier sections of the body, evenly support weight, and last at least 7 to 9 years. You can determine the best mattress for your sleep needs by considering your sleeping position and body weight—a mattress should be soft enough to alleviate pressure and firm enough to facilitate proper spinal alignment no matter how you sleep.

How do I choose a comfortable mattress firmness?

Choose mattress firmness based on your body weight and preferred sleep position for pressure point relief and consistent spinal alignment. For example, sleepers over 230 pounds will find themselves most comfortable on firmer mattresses since these beds don’t allow for much sinkage. On the other hand, petite sleepers will like softer beds better because they offer enhanced cushioning comfort.

How long is the Amerisleep sleep trial?

Each of our mattresses come with a 100-night sleep trial, a 20-year warranty, free shipping, and free returns. If you decide during your sleep trial that the mattress isn’t right for you, just give us a call, and we’ll arrange for it to be picked up free of charge and will issue a full refund.

How much does an Amerisleep California king size mattress cost?

We offer eight mattress models: five memory foam mattresses and three hybrids—our California king size mattresses range in price from $1199 to $1749.

Does an Amerisleep California king size mattress reduce back pain?

Our mattresses feature innovative pressure-relieving Bio-Pur® to alleviate aches and pains and prevent future discomfort. Bio-Pur® molds to the body to offer immediate cushioning comfort and relieve tension in throughout your body, especially in the back, shoulders, and hips.

Each of our mattresses (besides the hybrids and AS1) also features HIVE® technology, HIVE® offers zoned support to promote healthy spinal alignment and prevent backaches. HIVE® offers firm support under your torso, head, and feet to maintain healthy alignment and is softer under the shoulders and hips for improved pressure relief.

If you’re looking for the best mattress for back pain, consider our AS2, as it was previously voted by Business Insider as one of the best mattresses for back pain relief.

How often should you replace your Amerisleep California king size mattress?

Memory foam mattresses, on average, last about 7 to 10 years, whereas hybrid mattresses last 6 to 9 years, usually. We build our mattresses with highly-durable materials to help you get the most for your money. Plus, we offer a 20-year warranty with each of our beds, protecting you from manufacturing defects and sags.

What does the Amerisleep mattress warranty cover?

Each mattress comes with a 20-year warranty, covering sagging greater than 1.5” and any manufacturing defects causing damage to the mattress.

Alternatives to California King Mattresses

  • full mattress icon


    Best mattress for couples

    A Queen is perfect for couples with limited room space or single sleepers who prefer the extra room to get comfortable.

  • cal-king mattress icon


    Extra large master

    The King provides an additional 6 inches in width. They work well for extra large master bedrooms.

  • split-king mattress icon

    Split King

    Master bedrooms,
    adjustable beds

    Split-king beds enable couples to raise and lower the head and feet of their side of the bed independently.

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