Mattress Sizes and Bed Dimensions Guide
Mattress Size Guide
In this mattress size guide, we illustrate the mattress dimensions of all six standard mattress sizes—and some of the lesser-known options—to help you choose the best mattress for your needs.
Twin Mattress
Dimensions: 38” x 75”
A Twin mattress measures 38 inches wide by 75 inches long and is the smallest standard bed sold in the U.S. That footprint fits comfortably in a child's bedroom, a bunk bed frame, or a studio apartment where floor space is a constraint. It is not a practical choice for adults over 5'10", and it won't work for two sleepers regardless of how friendly they are.
Best for:
kids, bunk beds or single sleepers.
Minimum room size:
The minimum room size for a twin bed to fit naturally is 7 x 9 feet. But if you're looking to outfit the room with cozy accessories like a desk and dresser, an 8 x 10 square foot room may be required for the bed to fit more comfortably.
Twin Xl Mattress
Dimensions: 38” x 80”
A Twin XL mattress measures 38 inches wide by 80 inches long. It carries the same narrow width as a standard Twin but adds 5 inches of length — enough to make a real difference for sleepers between 5'10" and 6'5". It is the default size in college dormitory rooms across the country, which is why most dorm bedding is sized to fit it. Two Twin XL mattresses pushed together form a Split King, a configuration used with adjustable bed frames so two sleepers can set different head and foot elevations independently.
Best for:
taller teenagers, single adults or anyone with limited space.
Minimum room size:
8x10 feet. Narrow rooms of at least 7 feet wide can also work if the bed is placed along the longer wall.
Full Mattress
Dimensions: 53” x 75”
A full mattress (also called a double) measures 53 inches wide by 75 inches long. It gives a single sleeper 15 more inches of width than a twin, which is meaningful if you sleep with your arms out or shift positions often. For two adults, a full provides each person roughly 26.5 inches of horizontal space, which is narrower than most people's shoulders. It works for couples who genuinely don't mind being close, but anyone who describes themselves as a light sleeper or a restless sleeper will probably find themselves reaching for a Queen within a year.
Best for:
young adults, couples who like to cuddle or guest rooms.
Minimum room size:
9 x 11 feet minimum for a full bed to fit comfortably.
Mattress Thickness Chart
As you sleep, your body sinks into the material of the mattress. A thick mattress—let’s say 10 inches—gives manufacturers more room to design a supportive cushion.
Deep/Thick Mattresses
These mattresses are extra deep and often considered a luxurious choice. Our most luxurious mattresses like the Dream Max and Snow Max fall within the deep profile. They are both designed with unique comfort layers composed of different materials that increase the durability, support, and comfortability of the mattress.
Medium or Standard
Profile Mattresses
These mattresses are lush and supportive and generally suited for all sleeping types. The One has a standard profile and is the perfect addition to any bedroom.
Low Profile Mattresses
Realistically, mattress buyers should not buy a mattress that’s less than 6-inches thick—they have very few design capabilities to provide adequate support and pressure relief. Side-sleepers will usually sink about 5 inches into the mattress, which means a 6-inch mattress would bottom out. Low profile mattresses may work for younger children who may not sink into the mattress much or for short term use in guest rooms. However, low profile mattresses are not ideal for long-term comfort.
AIDE AU CHOIX
Frequently Asked Questions
Does Casper offer free mattress returns?
Yes. Mattress returns are free within the 100-night trial (after the 30-night adjustment period). We schedule a courier to remove the mattress from your home at no cost to you, and your original payment method is refunded in full.
What should I expect during my mattress’s adjustment period?
The Extra Firm Mattress is rated Extra Firm at 8.5/10, designed for sleepers who prefer a more supportive surface.
Is The Extra Firm Mattress Good For Back Pain?
A firmer surface can help keep your spine aligned. Many back and stomach sleepers prefer extra firm support, but comfort is personal.
How Long Does It Take For The Mattress To Fully Expand?
Unroll it onto your bed base and give it a few hours to regain its shape. Most mattresses fully expand within 24–72 hours.
Can I Try The Extra Firm Mattress Risk-Free?
Yes. You can try it at home with our 30-day risk-free money-back guarantee.
Does The Extra Firm Mattress Sleep Hot?
The cover and foam layers are designed to stay breathable so heat can move away from the body while you sleep.
Do I Need A Box Spring?
No. Place it on a solid slatted base, platform bed, or compatible foundation. A traditional box spring is not required.
