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What Is A Split King Mattress?

A comprehensive explanation about split king mattresses, including why you might want to sleep on split king mattresses, and what to expect while shopping for this kind of bed set-up.

Some bed sizing is pretty self-explanatory, but if you’ve heard the phrase “split king,” you might be a bit confused. We will explain everything that you need to know about split king mattresses, including dimensions, pricing, bed frames and bedding recommendations.

If the thought of a “split” king mattress has you thinking about 60s sitcoms with couples sleeping in separate beds, we have a few things to clear up for you. Split king mattresses are not the most common type of bed configuration, but they might be a really good option, especially for couples with very different sleeping preferences. Fear not though, you can go the route of a split king mattress and still snuggle up with your honey.

No need to sleep separately when you go for a split king mattress
No need to sleep separately when you go for a split king mattress

Our goal is to help you understand all the jargon that exists out there in the mattress industry and help you figure out what kind of bed will work best for you and your loved ones. Hopefully we can help you get to sleeping soundly soon!

Overview Of Sizes

All bed sizes boil down to two simple things: length and width. The most common length for a mattress is 80” which is just over six and a half feet. Twin XL mattresses, queen size mattresses and king size mattresses are all 80” long, making them an ideal choice for the majority of adults, as the average height for an adult male is about 5’8” and the average size for an adult female is about 5′ 4″. 

If you happen to be on the taller side though, there is also the option of a California king size mattress, which is 4 inches longer than a normal king size. This means it is 7 feet long!

Twin mattresses and full (also known as double) mattresses are four to five inches shorter than a king or queen size bed. Twin mattresses, especially, are a great choice for children, who are shorter than the average adult and therefore don’t need as long of a bed. These two shorter beds are also a good choice for single individuals, especially those who are shorter than 6 foot. 

So, if king, queen, and twin XL mattresses are all the same length, how are their sizes differentiated? Width! King size beds are the widest type of mattress, at 76” wide while twin XL and twin sized mattresses are the narrowest, at 38”. California kings, which have the same surface area as typical kings but have the dimensions distributed slighted differently, are 4 inches narrower, at 72”. Queen mattresses are a bit narrower than kings and cal kings, at 60”, and full sized mattresses are narrower still, at 54”. 

We typically recommend queen size and up for couples as this will give each sleeper at least 30” of space to themselves. It is not uncommon, though, for couples to share a full size mattress, you just might have to be a little bit more used to cuddling if you go this route.

Now, to answer the question that we’ve all been waiting for, what are the dimensions of a split king bed? Well, if you were paying attention to the numbers above, you might have already figured it out, but a split king is actually two twin XL mattresses put together on a king size bed frame.  Twin XL mattresses and king mattresses are both 80” long, and twin mattresses are half as wide as king mattresses. Take two 38” wide twin XL mattresses, stick them together, do a little bit of math magic and voila, you’ve got a 76” king size mattress. Whoever decided on the standard mattress sizes was pretty clever with this one, wouldn’t you say?

Is A Split King Right For Everyone?

No, probably not. First and foremost, this is really only something that we’d recommend for couplesIf you are single, you probably don’t even need a bed as big as a king, but if you want a huge mattress, having your bed split down the middle for no reason will probably be pretty annoying.

split king mattress #2
Couples can choose the mattress that works best for their individual sleep needs while still being close together at night

Also, couples who have a similar body type, sleeping style and/or mattress preference might not find getting a split king to be that necessary. If you are both going to want the same mattress, you might as well just get one big king size mattress. This will also typically be a bit more of an affordable bed, as buying two twin XL mattresses can often be a little bit more expensive than buying one king size mattress. 

Benefits Of Split King Beds

Why bother with two mattresses when you can just buy one king size one? There are actually several reasons why this set-up might work well for certain couples.

First of all, going the route of a split king can be really useful if you live in a smaller space, a walk-up apartment, or are planning on moving soon and/or frequently. Why? Because two twin XL size mattresses are a lot easier to move and get up stairs or around tight corners than a cumbersome king mattress would be. 

Split kings are also a great choice for couples who sleep vastly differently. For example, if you are a 6’6” bodybuilder who sweats through your sheets even in the wintertime, you will probably lean more towards a firm and supportive mattress that works to actively cool you down at night, such as Brooklyn Bedding Aurora.

If this bodybuilder is married to a petite person who prefers to sleep on their side under a mountain of blankets though, some issues might arise when trying to compromise on a mattress because smaller sleepers tend to sleep better of soft and fluffy beds, like the Tuft & Needle Mint mattress. With a split king, both people can get the mattress that will work best for them.

Another reason that couples might want their own mattress is motion transfer. We find that most mattresses will fair pretty well in this category, unless they are an older model with innersprings, which have mostly been replaced with pocketed coils in recent years. Sometimes though, you might have a partner that rolls around a lot in their sleep or gets up frequently for bathroom breaks or late night snacking. The motion from their side of the bed can transfer to your side and wake you up if you are sleeping on a connected mattress that has poor motion isolation. This problem is solved for couples who opt for separate mattresses: no more getting out of bed in slow motion to try to avoid waking your partner up.

Split king mattresses are also ideal for folks who want to buy an adjustable bed frame. Most king size adjustable bed frames come with the option of a split version, which means both sides of the bed can move independently. It stands to reason, then, that if you are going to get a frame that can move like this, you’ll probably need your mattresses to be able to move independently as well. If you stick a king size mattress on a split king size adjustable frame, you will only be able to move the frame with both sides in sync, or else your mattress will turn into a slide.

Why Opt For An Adjustable Bed Frame?

This kind of bed frame has grown in popularity a lot in recent years because adjustable bed frames often come with a lot of special features and can even be helpful in treating certain health conditions. For example, if you snore or suffer from sleep apnea, you can program your bed frame to raise 10°, which should improve your breathing. Some bed frames also come with massage features, a zero gravity setting, and even USB ports for easy phone charging while you sleep, among other things. 

tempurpedic sealy adjustable bed frame base
An adjustable bed frame is a huge win for split king owners

These bed frames are also often made to fit inside of your existing bed frame and will take the place of a traditional foundation, platform, box spring, or wooden slats. There is no need to compromise on the style of your room for the comfort of an adjustable frame.

If you go for an adjustable bed frame with split king mattresses, you will likely find that you and your partner are both able to find the ideal sleep setting for you. One person can sleep soundly on their soft foam mattress while the bed frame gently vibrates to massage their feet, while the other person can feel supported and cool on their firm latex mattress that is lifted to the perfect angle to avoid waking themselves (or their partner) up in the middle of the night with their loud snoring. 

What Kind Of Bedding Should I Use For My Split King Bed?

There are a few ways that you can go in terms of bedding for a split king, you can basically treat the set up like a normal king mattress or like two XL twin mattresses, or a combination of the two. 

Specifically for split king beds on adjustable bases, there are actually sheet sets that are made to cater to this unique sleep set-up. Split-top king sheets are fitted sheets that are the size of a normal king sheet and are connected at the tail end of the sheet like any other king sheet would be. At the head side of the sheet, however, these sheets split off into two twin size fitted sheets so that the adjustable bed frame can move freely on either side without pulling the fitted sheet off the other mattress.

If you are having a hard time imagining what this looks like, these sheets are sort of shaped like the letter U, connected at the bottom but branching off into two sides at the top. It may be a bit difficult to find sheets like this, though, so you can also just opt for two twin XL fitted sheets, which will essentially accomplish that same goal for your adjustable bed.

If your split king is not on an adjustable bed frame, you can either get twin XL sheets for each mattress, or cover them both in a normal king size sheet set, which will likely make the mattresses feel a bit more cohesive.

In terms of top sheets and comforters, some people will opt for separate blankets for each bed, or a king size blanket set to, again, make the mattresses a bit more cohesive. This will really be up to your judgement. If you know that one partner is a chronic blanket stealer, going for separate blankets might be a good bet. Some folks, though, might find that having separate blankets makes it harder to snuggle or feel close to their sleeping partner. 

Ultimately, as with all bed-related decisions, we encourage you to have a conversation about the things that are most important to you. Good sleep can do wonders for your health and (if you ask us) your relationship too. 

Buying Split King Beds

If you’ve decided that a split king bed is a good idea for you and your partner, the next step is to decide on the mattress or mattresses that you are going to buy. There are a lot of options with a split king, so a few things to keep in mind are price, size and preference.

First of all, price can play a huge role in your mattress buying decision. As stated before, buying two twin XL mattresses can be a little bit more expensive than buying one king mattress, but, if you are smart about it, it can also be a cheaper option.

If you and your partner both decide on a fairly luxurious mattress, take Helix Luxe, for example–this line of beds is great for a split king set up, because you can both find the Helix bed that caters to you–the pricing might blow your budget a little. The MSRP of a king size Helix Luxe bed is around $2,200 and the MSRP of a twin XL is around $1,250. If you buy two twin XLs, the price will be around $2,500—a fair bit more than for just the king. 

If, however, you choose completely different mattresses, say one person has back issues and goes for the around $1,600 Casper Wave mattress while the other person could sleep on anything so decides that Amazon’s $350 Lucid mattress will be just fine for them, you’ll save a lot more money than if you’d bought the king size Casper Wave at around $2,800. 

If you decide to buy totally different mattresses, one thing to keep in mind is the bed’s height. In general, most mattresses that we see are around 10” or 11” tall, but we have also seen some that are a fair bit shorter and some that are taller. For example, pairing the 9.25” tall Purple original with a 15” tall DreamCloud mattress will probably end up making your bed look and feel pretty funny. Make sure both mattresses are around the same height to avoid any peaks or valleys from forming in the intersection between the two beds.