California King vs. Full: What’s the Difference?

By Geoff McKinnen Certified Sleep Coach

Last Updated On December 14th, 2023
California King vs. Full: What’s the Difference?

The California king is the longest of all standard size mattresses, while the full mattress is one of the shortest. The Cal king beds are popular among couples and tall people, while full mattresses are good for average size single sleepers.

In this article, we discuss the main differences between these two standard sizes and help you choose the perfect size mattress for yourself.

Save $450 On Any Mattress

Plus free shipping

Get $450 OFF Mattresses

What is a California King Size Mattress?

A California king mattress measures 72 inches by 84 inches. It is 4 inches longer and 4 inches narrower than a regular king, which is also called the Eastern king. The extra-long Cal king size bed is an ideal choice for tall people.

Since the Cal king bed was first manufactured by a Los Angeles mattress merchant, the name of the state is associated with this bed size. A Cal king is also called the Western king because it originated on the west coast.

A Cal king bed has ample space for a couple and can comfortably accommodate children if they want to sleep with their parents on some nights. Compared to a full, these big Cal king beds are expensive. The average price of a Cal king mattress is $1500, but you’ll find mattresses priced higher or lower than this because the price depends on the quality of the materials used to make the mattress.

Full vs California King

A California king bed is also available in a split Cal king version. A split Cal king mattress is a regular Cal king size split in half, allowing each sleeper to choose different firmness levels on their side of the bed. The split versions work well with adjustable bases too, as they let you elevate your head and feet according to your preference without bothering your partner.


  • Spacious enough for couples, can fit children as well
  • An excellent option for tall sleepers
  • Available in split versions, allowing comfort customization for both sleepers


  • Doesn’t fit in smaller rooms
  • Expensive

What is a Full Size Mattress?

A full size mattress measures 54 inches by 75 inches and is popularly called the double bed. Before the introduction of the queen, king, and Cal king beds, full beds were popular among couples, so they got the name “double beds.”

Up until the 1940s, Americans were mainly sleeping on twin and full size mattresses. A twin was used as a single bed, while the full served as a double bed.

In the late 1940s, the country witnessed an economic boom, enhancing the buying power of Americans. The American people needed larger sized beds to furnish their big bedrooms in huge houses. Later, in the 1950s, the average height and weight of Americans were increasing, adding to the demand for bigger beds.

With so many larger sized mattresses available on the market, the full size is now used by single sleepers who don’t have enough space in their room. Technically, two adults can sleep on a full mattress in a pinch, but we can’t recommend it as a long-term sleep solution.

Though called the double bed, it doesn’t have ample room for two adults to sleep comfortably, giving each partner a space that’s largely the size of a crib mattress. At most, it can accommodate an adult and a child.

Full size mattresses are common in guest rooms, smaller bedrooms, or studios, where space is limited. On average, a full size mattress costs $1000, but the price depends on the quality of the materials.

Sometimes, full beds are used in the children’s rooms because they can easily accommodate two children. They are often used on the lower bunk in some bunk beds. Bunk beds optimize space, leaving more room for children to play.


  • A smart option for those with limited space
  • Available as bunk beds


  • Not long enough for tall people to sleep comfortably
  • Can’t accommodate two adults

Best Amerisleep Mattresses

Quick Guide: A 30-Second Summary

Best Mattress Overall Amerisleep AS3
Best Full Size Mattress Amerisleep Organica
Best California King Size Mattress Amerisleep AS5 Hybrid

Our Amerisleep mattresses are available in all of the standard sizes, including full and California king sizes. Each one of our mattresses can suit the individual needs of different sleepers, regardless of the size chosen.

Our most versatile and popular mattress is the AS3, created to establish a medium feel suitable for most sleeping styles. This mattress can provide unbeatable comfort, regardless of what size you choose.

Mattress Highlights
  • Bio-Pur® memory foam doesn’t off-gas or contain harmful chemicals
  • HIVE® zoned technology relieves pressure point pain
  • Bio-Core® base promotes a healthy spine
Recommended For
  • Most sleeping positions
  • Couples
  • Children and teens
  • Guest bedrooms

One of the best mattresses available in both full and California king sizes is the Amerisleep AS3. It works well for all types of sleepers in all types of mattress sizes. Need a bed for your child or preteen? Try the AS3. Need a bed for guests? Try the AS3. Need a bed for you and a partner? Try the AS3. The opportunities are endless with the AS3.

Inside the AS3 is our Bio-Pur® memory foam. Most memory foams are made from petroleum, which results in chemical-smelling, hot, and sag-prone mattresses. Bio-Pur® is made mostly out of castor oil, resulting in a durable, breathable, and fresh-scented bed. It relieves pressure just as well as other memory foam mattresses, but it won’t cause you to sink in bed.

The AS3’s second layer is made from Affinity foam and features HIVE®, our support technology with five ergonomic zones. HIVE® helps evenly distribute your body weight to reduce pressure point pain.

At the bottom of the AS3 is Bio-Core® foam, which supports your spine and prolongs your mattress’s lifespan.

Another great part of the AS3 is that it comes in both foam and spring variations. The AS3 Hybrid contains pocketed coils and a thin foam base instead of Bio-Core®, resulting in a uniquely springy and supportive bed.

All Amerisleep mattresses, including the AS3, include free shipping and returns, a 100-night trial, and a 20-year warranty.

Quick Summary

  • Comes in both foam and spring models
  • Amerisleep’s best-selling mattress
  • Has a balance of support and cushioning
Save $300 on the Amerisleep AS3 with our discount code
Shop Now

While all our mattresses are designed to be eco-friendly, our Organica mattress contains the highest concentration of natural materials. Excellent for solo sleepers who want an expansive and sustainably produced mattress.

Mattress Highlights
  • Talalay latex is soft, yet supportive and lifting
  • Pocketed coils are reinforced for reliable edge support
  • Dunlop latex promotes longevity and limits sagging
Recommended For
  • Most sleeping positions
  • Couples
  • Eco-conscious shoppers
  • Hot sleepers

A great full-size mattress option is our Organica mattress, a sustainably-produced bed great for all sleepers. At 13 inches thick, the Organica has a medium feel and contains wool, two types of latex, and pocketed coils.

At the top of the Organica is New Zealand Joma Wool®, which isn’t just another layer of cushioning. Wool is both a natural thermo-regulator and fire retardant. This means sleeping on wool will keep you and your bed both cool and safe in the event of a fire.

Next is a Talalay latex comfort layer. It’s breathable and springy, yet still soft and pressure-relieving. It’s not quite as “hug-like” as memory foam, but it makes up for this with its extra bounciness.

We use pocketed coils in the Organica to take it to another level of breathability, supportiveness, and bounciness. The steel springs isolate motion while offering isolated support for your spine and back. Beneath the coil layer is Dunlop latex, which protects the springs and maintains your bed’s structural integrity.

We sought four certifications for the materials inside the mattress:

Like all Amerisleep mattresses, the Organica comes with a 100-night sleep trial and a 20-year warranty.

Quick Summary

  • Contains both natural Talalay and Dunlop latex
  • Made with organic and sustainably-sourced materials
  • Free of fiberglass and chemical flame barriers
Save $300 on the Amerisleep Organica with our discount code
Shop Now

The softest model we offer is the AS5, created to offer a plush feel for single sleepers and couples. Side sleepers will particularly enjoy how the mattress embraces their curves.

Mattress Highlights
  • Active Flex adapts to your body to relieve pressure
  • Pocketed coils align the spine and isolate motion
  • Base foam protects coils to boost mattress longevity
Recommended For
  • Side sleepers
  • Couples
  • Petite to plus-sized people

The most luxurious California king size mattress we offer is the Amerisleep AS5 Hybrid. It’s our softest and thickest mattress, yet we manage to make it supportive and cooling.

Inside the AS5 Hybrid is Bio-Pur® memory foam, the same material in the AS3 we mentioned earlier and in many other Amerisleep beds. What makes the AS5 Hybrid different from our other beds is its Active Flex transition layer.

Active Flex is a latex-like material designed to enhance the AS5 Hybrid’s softness and support without making it feel overly firm. It prevents you from sinking into bed uncomfortably as well, making this bed one of our favorites for plus-sized people.

Beneath the Active Flex are hundreds of pocketed coils and base foam. The AS5 Hybrid is another one of our beds available in a foam model as well if you prefer less bounce and more cushioning. In the standard AS5 mattress, there is Bio-Core® foam rather than pocketed coils.

The AS5 is backed with a 100-night sleep trial and a 20-year warranty.

Quick Summary

  • Comes in both foam and spring models
  • Soft, yet supportive for all sleepers and body types
  • Contains flexible and motion-isolating coils
Save $300 on the Amerisleep AS5 Hybrid with our discount code
Shop Now

Size Comparison of California King and Full Size Mattresses

A California king bed is 18 inches wider and 9 inches longer than a full bed, making it a good choice for couples.

A full bed doesn’t provide adequate space for a couple, but it is a good option for single sleepers who don’t have the budget or space for a queen bed in their room, like young adults living in a studio bedroom apartment.

ParametersCalifornia kingFull
Mattress Dimensions (IN)72 inches by 84 inches54 inches by 75 inches
Mattress Dimensions (CMs)182.88 cm by 213.36 cm137.16 cm by 190.5 cm
Recommended Room Size (FT)12 feet by 12 feet10 feet by 10 feet
Recommended Room Size (CM)365.76 cm by 365.76 cm304.8 cm by 304.8 cm
Common inBig master bedroomsGuest rooms, children’s rooms, and studios
Suitable forCouples and tall sleepersSingle adults and children

Other Standard Sizes

If the California king or the full size does not suit your sleep needs, there are other popular mattress sizes available online or in mattress stores. When buying a mattress, factor in the space taken up by other essential bedroom furniture such as lamps, nightstands, and a dresser.

Ideally, leaving 2 to 3 feet of space on all three sides (except the side against the wall) of your bed makes your room look neat. This set-up also leaves you with sufficient walking space. Following are the other standard mattress sizes:

Twin Size Mattress

Dimensions: 38 inches by 75 inches

A twin size mattress is 16 inches narrower than a full so they don’t need as much room space. This compact size mattress can even fit in a room measuring 7 feet by 10 feet, but its short length cannot accommodate tall sleepers. A twin is the same length as a full bed.

A twin bed is a good option in a child’s room. A child usually graduates from a crib to a twin bed. Families with more than one child often use bunk beds available in twin and twin XL sizes.

Twin XL Size Mattress

Dimensions: 38 inches by 80 inches

A twin XL size mattress is 5 inches longer than a twin and full, making it a better choice for taller people. The extra length comes in handy to accommodate growing teenagers as well. Twin XL beds are common in children’s rooms, college dorm rooms, and shared bedrooms.

See our twin vs twin XL mattress guide if you want an in-depth comparison of the two sizes.

Queen Size Mattress

Dimensions: 60 inches by 80 inches

A queen size bed is 6 inches wider and 5 inches longer than a full. It’s the ideal option for single sleepers because it allows sufficient space to stretch out while sleeping. The queen bed is also used as a couple bed, allowing each sleeper 30 inches by 80 inches of space. Though a queen is not as spacious as a Cal king bed, it’s the right size for couples who don’t have large bedrooms for bigger beds.

Full and queen mattresses are often compared to each other because of their similar dimensions.

King Size Mattress

Dimensions: 76 inches by 80 inches

A king size mattress is the widest of all standard size mattresses. It is 4 inches wider but 4 inches shorter than a Cal king. A king bed is the perfect size for couples and it has enough room for small children as well.

Like Cal king beds, even standard king size mattresses are also available in split options. Since a twin XL mattress is the exact half of a king bed,  placing two twin XL mattresses side by side makes a split king mattress.


Which is a better option: a king or California king?

Both king and Cal king size beds have plenty of room for a couple, but a Cal king is 4 inches longer than the king. If you or your spouse need some extra legroom, a Cal king is a good option. Otherwise, a king size mattress is better because it is 4 inches wider than a California king size bed. If children want to sleep with parents some nights, then a king will be more spacious than a Cal king. Plus, the total surface area of a standard king is more than a Cal king bed.

Do two twin XL beds make a California king bed?

No, two twin XL beds placed side by side makes a king bed. A twin XL mattress is the exact half of a king bed, so placing two of them together makes a king, but a Cal king has different dimensions. A Cal king bed is narrower and longer than a king, so two twin XL mattresses will not add up to the size of a Cal king bed.

Do king size sheets fit a California king bed?

No, king sheets will not fit a Cal king bed. A standard king bed measures 76 inches by 80 inches, while a Cal king bed is 4 inches longer and narrower. A fitted sheet meant for a king bed will be too short and wide for a Cal king mattress. Cal king sheets are readily available online or in bedding stores. A Cal king is a standard mattress size, so finding compatible bedding accessories is not difficult.

Is a full size bed good for couples?

No, a full size does not have adequate space for a couple. It can fit an adult and a child but will be too small for two adults. In fact, some couples feel cramped even in a queen, which is 6 inches wider than a full bed.

Is a full size bed the same as a queen?

No, a full size bed is 6 inches narrower and 5 inches shorter than a queen. A full mattress is a good option for single sleepers who don’t have sufficient space for a queen, while a queen size mattress can be used by both single sleepers and couples. Though a queen bed is not the best option for couples, it’s the right fit in small master bedrooms.


The Cal king and the full cater to different sleeper needs. While the Cal king is always the best option for tall sleepers because no one likes to sleep with their feet dangling out of the bed, the full size mattress is good for average size single sleepers. Finding the right size mattress for yourself is crucial to a good night’s sleep. If you don’t get enough space to stretch out and relax your muscles while sleeping, your sleep quality gets affected and poor sleep causes daytime drowsiness, impairing productivity.

About the author

Geoff McKinnen is a writer focusing mainly on the healthcare industry and has written articles on everything from foods to help you lose weight to the connection between Alzheimer’s and sleep. Geoff’s passionate about helping readers improve their well-being to lead happier lives. Outside of work, Geoff enjoys cycling and hiking and believes that by leading a healthy lifestyle, he can help others do the same.

View all posts

Discover the ultimate sleep system

Choose your mattress

Shop top-rated mattresses with proven sleep-boosting materials.

Get a pillow

We have the perfect pillow to pair with your mattress.

Browse Pillows

Pick out bedding

Bring out the best in your mattress with our soft and breathable bedding.

Browse Bedding