Selecting the right bed size is a huge part of the mattress buying process. For many sleepers, it can be a habit to stick with the same mattress size as what you had before when it’s time to replace, but things change—sleepers change.
Are you an active sleeper? Do you have animals or children sharing the bed with you? Do you have a partner? You may also want to consider if your bedroom size changes if your mattress size should change as well. These are just a few of the simple questions to ask yourself when deciding what mattress size is right for you.
This guide breaks down each mattress and bed size dimensions and specs to give you all the details and help you decide which is the best fit for you and your space. Once you have the sizing down, take our mattress quiz to get a better idea of the best mattresses for your sleep preferences.
Twin Size Bed Dimensions
A Twin size mattress is typically 38” W x 75” L. This is the smallest of adult-size mattresses. A Twin size mattress would be suitable for a child who has outgrown the toddler bed, a single adult, or those with small bedrooms.
This size is commonly used for daybeds, bunk beds, dorm rooms, or a small guest bedroom.
This is also the smallest mattress for most of the popular online mattress companies. For sleepers tight on budget or space, a Twin size mattress can provide the same luxury feel of a larger mattress, without costing as much or taking up as much room.
Twin XL Size Bed Dimensions
A Twin XL size mattress is 38” W x 80” L. This mattress is the same width as a traditional twin but is 5” longer in length. This is great for tall adults who do not have room for a wider bed. Not all sheets or comforters come available in Twin XL, so be sure to double-check and know the difference before shopping for bedding.
Can you use two Twin XL mattresses on a King size frame?
The short answer is yes. Two Twin XL mattresses make up the dimensions of one King size mattress. This is a popular strategy for sleeping partners who have a very different feel or firm preferences. Joining two mattresses together on a single frame is also a nice option for sleepers who want to use an adjustable frame. The separate mattresses allow sleepers to sit up or lie back without disrupting their partner. If you do opt for 2 Twin XL mattresses on a King frame you can either use individual Twin XL bedding sets or a single King size sheet set.
Full-Size Bed Dimensions
A Full-size mattress is 54” W x 75” L. This size mattress may also be referred to as a “standard double.” For single active sleepers who like to sprawl out or couples who have a small bedroom, a Full-size mattress may be suitable. A Full or double-size mattress may be a tight squeeze for couples who share the bed with children or pets.
Here are some specs to think about when considering a Full-size mattress:
- For single sleepers, that is 54” of sleeping space.
- For partners, that is 27” of sleeping space per person (11” less than a Twin size mattress).
- A 6’ tall sleeper would have only 3” of extra space if fully extended on this mattress.
Queen Size Bed Dimensions
A Queen size mattress is 60” W x 80” L. This is the most popular mattress size in the United States right now and is a comfortable fit for single active sleepers, couples, and those who may share the bed with children or pets. To comfortably fit a Queen mattress, it is recommended that your bedroom be at least 10’L x 10’W.
Some specs to consider:
- For single sleepers, that is 60” of sleeping space.
- For partners, that is 30” of sleeping space per person (8” less than a Twin size mattress).
- A 6’ tall sleeper would have 8” of extra space if fully extended on this mattress.
- See my top choices for the best queen-size mattresses.
King Size Bed Dimensions
A King size mattress is 76” W x 80” L. This mattress is extremely comfortable for single active sleepers as well as couples who share a bed with children or pets. To comfortably fit a King size mattress, it is recommended that your bedroom be at least 12’W x 12’W.
For comparison’s sake, a King size mattress is the same size as two Twin XL mattresses. If you and your partner share a bed but have very different sleeping preferences, the Split King could be a nice option since it allows each side of the bed to be distinctively different feels. Split King mattresses are also good choices for sleepers who are considering adjustable bed frames.
Consider the following specs before purchasing a King size mattress:
- For single sleepers, it’s 76” of sleeping space.
- For partners, it’s 38” of sleeping space per person (the same width as a Twin size mattress).
- A 6’ tall sleeper would have 8” of extra space if fully extended on this mattress (the same length as a Queen size mattress).
- Check out my picks for the best king size mattresses of the year!
Split King Size Bed Dimensions
A Split King size mattress uses two identical-sized mattresses—each 38”W x 80”L—which equals the size of a complete King size mattress. Sleepers who benefit from a Split King bed often have very different sleeping preferences than their partner. The split mattress allows sleepers to have a mattress that is individually right for them, without sacrificing the sleep of their partner.
Some Split King beds are joined at the bottom half of the mattress and only split at the top. This style is more for sleepers who do not have different sleep preferences, since the interior of the mattress is the same throughout. Some couples may also opt for a flippable mattress that offers a different firmness on each side, such as the Layla mattress.
The benefit of this style of mattress is that, when used on an adjustable frame, each side of the mattress can move independently, allowing sleepers to sit up or lie back without disturbing their partner. The obvious drawback here is finding sheets to fit this style of mattress. These sheets are usually very expensive and may be hard to find.
California King Size Bed Dimensions
A California King size mattress is 72” W x 84”. This mattress is great for sleepers who are very tall or just want a little extra length to the mattress. It is extremely spacious for active sleepers or couples who may sleep with children or pets. While the California King mattress is 4” longer in length, it is actually narrower than a standard King size mattress by 4”. To comfortably fit a California King size mattress, it is recommended that your bedroom be at least 12’W x 12’L.
These specs mean:
- For single sleepers, that is 72” of sleeping space.
- For partners, that is 36” of sleeping space per person (2” less than a Twin size mattress).
- A 6’ tall sleeper would have 12” of extra space if fully extended on this mattress.
What size mattress do I need?
When deciding which mattress is the right fit for you and your space, be sure to consider some of the following factors:
What is the size of your room?
To fit a Queen size bed, your room should be at least 10’x10’. The following scaled images can give you an idea of the footprint a Queen size bed/mattress will take up in both a 10×10′ bedroom and a 12×12′ bedroom.
To fit a King size bed or California King size bed, your room should be at least 12’x12’. The two images below will give you a good idea of how large a King size mattress/bed is in relation to a 10×10′ room and 12×12′ room.
Who will be sleeping in the bed?
Children, depending on age, will likely be most comfortable in the following mattresses:
- Twin bed
- Twin XL
MORE: Best mattress for kids
Single adults will likely be most comfortable in the following size mattresses:
- Twin XL
Beds with two adult sleepers will likely be most comfortable in the following size mattresses:
- California King
Beds with two adult sleepers and children or pets will likely be most comfortable in the following size mattresses:
- California King
Sleepers who want a mattress that will work with an adjustable frame (to move each side independently) should consider the following mattress sizes:
- (2) Twin XL mattresses
- Split King
Mattress & Bed Dimensions Summary
There are many different styles and mattress/bed sizes out there, and there is no right or wrong answer as to which one is right for you. Considering room size, sleeper size, future growth, and personal preference are all factors that can help you determine which size mattress would be the best fit for you.
Understanding mattress size dimensions and specs allow you to understand each mattress format and make the best decision for you.