Before buying a new mattress, there are many factors to consider, such as material, firmness and cost — but the first decision you have to make is size. Most mattresses are available in Twin, Full, Queen, King and California King sizes with some stores offering crib and Twin XL sizes too.
The Good Housekeeping Institute Textiles Lab consists of bedding experts who evaluate mattresses, sheets, pillows and comforters. Here, our pros explain the differences between standard mattress sizes to make it easier than ever to find your dream bed. While these are the standard dimensions, sometimes there will be slight differences brand to brand. It’s always best to confirm the specific dimensions of the mattress before buying — especially important to compare the mattress size to bed frame dimensions.
What are the differences between mattress sizes?
CRIB
Dimensions: 27” x 52”
Crib mattresses are designed to fit perfectly in a standard crib, suitable for babies and toddlers. They’re available as a foam or innerspring mattress like adult mattresses, but they tend to be firmer for safety reasons.
TWIN
Dimensions: 38” x 75”
Once your child graduates from a crib, they’ll likely move to a “big kid bed,” where you’ll need a Twin mattress. Best for kids or other single sleepers, a Twin is also the best mattress size for bunk beds.
TWIN XL
Dimensions: 38” x 80”
A bit longer than a twin, a Twin XL mattress is typically found in college dorms and is best for tall children, teenagers or other solo sleepers. It's five inches longer than a standard Twin mattress, so it gives more room for taller folks to spread out. Note that Twin XL mattresses are less widely available than other sizes, but many brands offer Twin XL mattress toppers to help make dorm mattresses more comfortable.
FULL
Dimensions: 54” x 75”
A Full mattress offers a lot of space for single sleepers, so it's a popular choice for young adults. It's also the first size that can accommodate couples — though it will be a bit cramped for some — making it useful in smaller guest bedrooms.
QUEEN
Dimensions: 60” x 80”
Queen is the most popular mattress size on the market, as it’s perfect for couples. It offers ample space to spread out and allow kids and pets to sneak onto the bed sometimes.
KING
Dimensions: 76” x 80”
With a King mattress, each member of a couple gets about the width of a twin mattress to spread out and sleep comfortably. A King is best for couples who grew out of a Queen mattress or families who want space to all snuggle in bed.
CALIFORNIA KING
Dimensions: 72” x 84”
Four inches longer (but also narrower) than a King mattress, California Kings are the longest mattress style available, perfect for taller couples with kids (or pets who like to sleep at the foot of the bed). Note that this style is usually the most expensive.
How to find the right mattress size for you
Overall, a quality mattress can last for over a decade, so we recommend investing in a mattress you love. While it’ll ultimately come down to personal preference, the following are some considerations for deciding which mattress size is best for your needs:
- Room size: Measuring the space where your bed will go is a great way to make sure the mattress will fit nicely with the rest of your bedroom furniture. To have room for nightstands and to avoid having a cramped space, it’s best to leave about two feet of space on each side and at the end of the bed.
- Sleeping partners: If you sleep with a partner, both of you will have to agree on the best size. Couples usually start with a Queen size mattress, but if you're sharing the bed with pets or kids, you might want to size up, especially if you both prefer having more space and legroom.
- Height: If you’re very tall and still want ample legroom, a California King has the longest length. If you are under 6'5", a Queen or King size should provide enough length to sleep comfortably.
- Cost: Mattresses are a pricey purchase and only get more expensive the bigger they get. Remember that sheets also increase in price for bigger mattresses!
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Mattress sizing FAQs
What is the most popular mattress size?
Queen is the most popular mattress size as it can accommodate two people comfortably while not taking up too much space in the bedroom. It's also more affordable than a King, and sheets and bedding are widely available in Queen sizing.
How thick is the average mattress?
Mattresses typically range from 8 to 14 inches thick, though some more affordable styles are thinner. Most quality mattresses are at least 10 inches thick to provide adequate cushioning and support. If you have a thinner mattress, consider adding a mattress topper.
What is the difference between a King and California King mattresses?
They are both large mattresses with slightly different shapes. A King mattress (76" x 80") is 4 inches wider but 4 inches shorter than a California King (72" x 84").
Do two Twin mattresses equal a King mattress?
Many believe that two Twin mattresses pushed together make a Queen or King size mattress, but they actually don't create a traditional mattress size! Two side-by-side Twin mattresses are the same width as a King mattress, but they're 5 inches shorter in length.
How do I know my mattress size?
Using a measuring tape, measure the width and length of your mattress and compare it to the size chart above. Note that there are sometimes slight variations between brands. Also, it's helpful to measure the depth of the mattress when buying sheets too.
Emma Seymour
Textiles, Paper & Apparel Lab Senior Analyst
Emma Seymour (she/her) is a senior product analyst at the Good Housekeeping Institute's Textiles, Paper and Apparel Lab, where she has led testing for luggage, pillows, towels, tampons and more since 2018. She graduated from Cornell University with a bachelor of science in fiber science and apparel design and a minor in gerontology, completing research in the Body Scanner Lab on optimizing activewear for athletic performance.
