How to Measure a Mattress

By Geoff McKinnen Certified Sleep Coach

Last Updated On January 31st, 2024
How to Measure a Mattress

Do you need to buy a new bed frame or bedding accessory, but the size of your mattress is escaping your mind? You might be able to find the old mattress order and double-check its dimensions that way. However, that may not be the case for everyone.

Perhaps you misplaced the original mattress information, or perhaps the bed was a gift. Whatever the case, if you need to measure your mattress yourself, it’s a relatively quick and easy task. Within a few minutes, you can have all the needed size dimensions of your mattress.

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Measuring Your Mattress

The first step of measuring your mattress is removing any bedding that can interfere with your measurements. Strip off the sheets, blankets, and pillows. If you have a mattress topper, you may want to leave it on if you’re measuring for a fitted sheet set. Otherwise, you can remove the topper, too.

You may want to accomplish two tasks simultaneously and wash your sheets and blankets at this point. As a reminder, general bedding should be washed once a week. Regularly cleaning your bedding helps to prevent allergen build-up.

Once your bedding has been cleared away, take a tape measure or fabric ruler and measure right to left across the mattress to gauge its width. If your mattress curves outward on any side, you’ll want to measure it where the mattress sticks out the most. Repeat this method to obtain the mattress’s length, measuring from the widest point top to bottom.

If you want to know your mattress thickness as well, measure from the top of the mattress to the bottom. Depending on your bed frame, you may have to remove your mattress and set it on the floor to get an accurate measurement.

We recommend noting your measurements on a piece of scrap paper or using a smart device. That way, you won’t forget them later.

Standard Mattress Sizes

Once you have measured your mattress, you can figure out which mattress size it matches. However, if you have a custom-made mattress, your mattress may not correspond with any of these sizes. We discuss the more common non-standard mattress sizes in our next section.

Mattress SizeDimensions in Inches
Crib28 ⅝ inches by 52 ½ inches
Twin38 inches by 74 inches
Twin XL38 inches by 80 inches
Full54 inches by 75 inches
Queen60 inches by 80 inches
King76 inches by 80 inches
California King72 inches by 84 inches
Split KingTwo mattresses, each 38 inches by 80 inches


A standard crib mattress measures about 28 ⅝ inches by 52 ½ inches. Crib mattresses should be made in accordance with safety standards to minimize the risk of sudden infant death syndrome (SIDS). We recommend firm crib mattresses with springs to buoy a baby’s body.

Despite the fact that a crib mattress is a standard size, not every brand carries a crib mattress.


Twin size mattresses are the smallest standard size mattress we can recommend for adult sleepers. However, due to the mattress’s dimensions, we can’t recommend them for people over 6 feet tall.

Twin beds can squeeze into bedrooms about 7 feet by 9 feet. They’re perfect for people living in a studio apartment bedroom or seeking a smaller mattress for a daybed.

Twin XL

Twin XL size mattresses are a small step up from the standard twin mattress. They offer 5 more inches of width, perfect for sleepers who are a little over 6 feet tall.

As with a twin bed, you can squeeze a twin XL mattress into a smaller bedroom or guest room that’s about 7 feet by 9 feet.


Full size mattresses are the most expansive size we can recommend for single sleepers with smaller bedrooms or budgets. With the extra space of a full mattress, a solo sleeper can comfortably sprawl on the mattress. We do not recommend this size for couples, however, since each sleeper would have a sleeping space roughly as wide as a crib mattress.

Full or double beds can fit into rooms a little under 10 feet by 10 feet.


Queen size mattresses are a popular choice because they suit most sleepers and fit in most bedrooms. A queen size bed is the smallest mattress we can recommend for couples who want to share the bed. Single sleepers will also enjoy the sprawling space, particularly if they’re too tall to fit on a full mattress.

Our recommended room size for a queen bed is at least 10 feet by 10 feet.


King size mattresses are the largest mattresses that most mattress brands carry. Couples who desire their personal space may find a king mattress suits their needs better than a queen bed.

Our recommended room size for a king bed is about 12 feet by 12 feet.

California King

California king size mattresses are the longest standard mattress size. The size is made to accommodate sleepers over 6 ½ feet tall, preventing them from having to sleep with their feet hanging over the side.

As with a standard king mattress, our recommended room size for a California king size bed is 12 feet by 12 feet. See our California king vs king mattress guide for a deeper comparison of the two sizes.

Split King

As the name suggests, a split king size mattress is a king bed divided in half. Each side is equal to a twin XL mattress, so even if a brand doesn’t officially carry a split king bed, you can easily put one together with two twin XL mattresses.

Since a split king mattress has the same dimensions as a king bed, we don’t recommend putting it in a room smaller than 12 feet by 12 feet. See our split king vs king mattresses for an in-depth examination of the two sizes.

Non-Standard Mattress Sizes

Aside from the standard size mattresses, you may encounter a few variations, such as the full XL, a California or Olympic queen, or an oversized king mattress.

Mattress SizeDimensions (Width and Length)
Small Single30 inches by 75 inches
Full XL54 inches by 80 inches
California Queen60 inches by 84 inches
Olympic Queen66 inches by 80 inches
Wyoming King84 inches by 84 inches
Texas King80 inches by 98 inches
Alaskan King108 inches by 108 inches

The full XL and California queen sizes are designed as mattresses for taller sleepers. However, people too short for a full mattress may want to choose the far more common queen size, which will make it easier to find matching bedding.

Similarly, taller sleepers who want a mattress 7 feet long may prefer a California king to a California queen. However, a California queen bed may be necessary if they have a smaller bedroom that can’t accommodate a king mattress.

The Wyoming, Texas, and Alaskan king sizes are significantly larger than a standard king, too large for anything but the most expansive master bedrooms.

Some of the best RV mattresses also come in sizes shorter and thinner than a traditional mattress size. These reduced dimensions make the mattress more portable and decrease drag on the vehicle.

Our RV mattress size guide delves into the more common sizes and dimensions of a camper mattress.

Why Do I Need to Measure My Mattress?

Measuring your mattress is essential for making informed decisions about sleep accessories and ensuring a comfortable night’s rest. Moreover, precise measurements become crucial when assessing mattress sag for warranty claims.

Picking Out Matching Sleep Accessories

Measuring your mattress can be necessary if you’re shopping for new bedding. After all, it does no good to pick out the best bed frame or sheet set if they won’t properly fit your mattress.

Knowing your mattress’s measurements is essential when you’re picking out:

Loose bedding items such as blankets, comforters, and duvets are less restrictive since the extra fabric can simply hang over the mattress’s sides.

Bed Height

Understanding your mattress’s depth can also help you determine if your bed is at a comfortable height. Bed height is often an overlooked consideration, but it can affect how easily you move in and out of bed.

You can measure your bed height by holding a tape measure to the top of your mattress, then pulling the tape measuring down to the floor. If your mattress surface is uneven, you can measure from the highest point.

To check if you have a comfortable bed height, try sitting on the edge of your bed. Your feet should rest flat on the floor, and your knees should form a 90-degree angle.

If need be, you can raise or lower your bed. See also:

Warranty Claim

Lastly, you might also measure a mattress sag for a warranty claim, along with photos of the mattress sent off to customer service.

Start by grabbing a measuring tape or ruler. Put it at the edge of the sagging mattress and slide it to the lowest point of the sag or body impression. Write down this measurement. Do this in various spots on the mattress and find the average sag depth.

Keep in mind, the measurements need to be spot-on for your warranty claim to work. Mistakes in measurements might result in your claim getting rejected. Follow these steps closely to make sure your measurements are accurate.

Dimensions of an Amerisleep Mattress

All of our Amerisleep mattresses are offered in seven sizes. The dimensions of these sizes remain the same across mattress models.

Amerisleep Mattress SizeLength and Width (Inches)
Twin74 inches by 38 inches
Twin XL80 inches by 38 inches
Full75 inches by 54 inches
Queen80 inches by 60 inches
King80 inches by 76 inches
California King84 inches by 72 inches
Split KingTwo beds, each 80 inches by 38 inches

Our mattress models do vary in thickness, which will affect your total bed height and what sheets you can slip over your mattress. The table below lists each of their thickness for easy reference.

Model NameMattress Height
Amerisleep AS110 Inches
Amerisleep AS212 Inches
Amerisleep AS312 Inches
Amerisleep AS3 Hybrid12 Inches
Amerisleep AS412 Inches
Amerisleep Organica13 Inches
Amerisleep AS514 Inches
Amerisleep AS5 Hybrid14 Inches

As a side note, we never recommend mattresses under 10 inches thick for adult sleepers. Mattresses thinner than this may feel uncomfortable or unsupportive. Alternatively, because they contain less material than a thicker mattress, the bed may wear out within a few short years.

Other Measurements to Consider

If you’re looking to upgrade to the best mattress and are measuring your current mattress for that purpose, you may want to also measure your doorways and the dimensions of your hallways before you purchase the bed. Naturally, a mattress is no good if you can’t fit it into your bedroom.

However, this is less of an issue than it once was thanks to mattresses in a box, which are tucked into portable boxes and can be carried with relative ease into any room.

It’s also vital to understand what mattress foundation size you have. If you do not know for certain, you can measure it the way you would a mattress.

On a related note, while mattress sizes are relatively standardized, many matching accessories are not. For example, blankets, comforters and duvets for the same mattress size can have widely different measurements. All of them should be fairly larger than the mattress to let part of the bedding drape over the side, but how much larger it will be depends on the manufacturer.

See our comforter and bedding sizes guide and blanket sizes guide for more details.

Comparing Mattress Sizes

Frequently Asked Questions

How do you measure a mattress for a fitted sheet?

Once your mattress is completely bare of bedding, use a tape measure or flexible ruler to measure from the widest point of the mattress on its sides. After you obtain the measurements for its length and width, measure the mattress’s depth to get an idea of how deep a pocket your fitted sheets will need.

Do you have a mattress topper? You will have to add its depth to the mattress’s height since the fitted sheet will slip over both the topper and mattress.

What is a standard size mattress?

The standard mattress sizes are twin, twin XL, full, queen, king, California king, and split king. Some mattress brands only carry the first six, which can leave shoppers improvising a split king mattress by pushing two twin XL beds together.

Technically, a crib mattress is also considered a standard size, but as it is a size suitable only for infants and small children, it often goes unmentioned when listing off mattress sizes.

Is there a mattress smaller than a twin?

Yes, there are mattresses smaller than a standard twin size mattress. Perhaps the most common one is a crib mattress, which many parents move to a toddler bed until their child is ready for a twin bed. A crib mattress is usually around 27 to 28 inches wide and 51 to 52 inches wide.

Some RV twin or bunk mattresses are also smaller than a regular twin bed. This compact design helps travelers meet the vehicle’s weight limit while sleeping comfortably. There is also the small single size, measuring only 30 inches wide and 75 inches long.

Is a double bed the same as a queen?

No, a double bed is another word for a full size mattress, which is 5 inches narrower and 6 inches shorter than a queen bed. However, when it comes to bedding, many brands offer sheets, blankets, and comforters designed to fit over a full or queen size bed.

Single sleepers are typically equally comfortable on a full or queen size mattress. However, couples will need the space a queen mattress offers or even a larger king size mattress.

Do two single or twin beds make a king?

No, two twin beds together do not form a traditional king mattress or any other standard mattress size. However, two twin XL mattresses do form a split king size mattress. A split king mattress has a few advantages over a standard king bed, such as increased customization possibilities when paired with an adjustable bed.

Ready to Measure Your Mattress?

Measuring your mattress should only take a few minutes and it can save you so much time and hassle when it comes to sleep accessories. When you understand your mattress’s dimensions, there’s no need to worry about returning any bedding or a frame that doesn’t fit your mattress.

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.

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