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How To Convert Two Twin Beds To A King

In the fall I made few little updates to my daughter’s room, including supersizing her bed! This worked out so well that I thought I’d share some tips with you on how we were able to convert two twin beds to a king.

A guide for converting two twin sized mattresses to a king size.

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When we first moved here and did her room, Hannah was 10, and now she is a sophomore in high school and okay, MAYBE a scooch taller than me (even though this feels like a minute ago…..)

We didn’t do a big room makeover, but just tweaked it a bit so the room was less TWEEN and more FIFTEEN.
Getting a new mattress was at the top of our list of to-dos, and since Hannah absolutely adores to sleep, she had been trying to talk us into getting a queen size bed for the longest time, particularly because her older brother already has one. Even though I loved her sweet little girl twin bed dearly, it did make sense for us to have another big bed in the house that we could use when we have overnight guests (we don’t have a guest room so our kiddos get evicted when their grandparents or out of town family come to stay).
Between our three kids we had 2 twin size beds with trundles underneath, and it occurred to me that those two trundle mattresses that had only been used occasionally for kid sleepovers could make up a king sized bed that would be great for guests – and also make Hannah’s dreams of a humungous bed come true!
I searched online about how to make two twin beds into a king and came up short on some details, so I thought it might be helpful to share what I learned in the process.
Tutorial on how to convert two twin beds to a king.


2 regular twins do NOT equal a king (but it can work). I had always heard that two twins equal a king in size and this is true with 2 twin XL (extra long) mattresses (like colleges) but NOT with regular twin mattresses.
• 2 twin XL mattresses together are the same width & length as a king (76″x80″) however
• 2 regular twin mattress are the same width but shorter in length than a king by 5″ (76″x75″).
Our twin mattresses are regular size, 38″x75″ and they worked out just fine. Keep reading to see how I compensated for those 5″.



bed platform alleviates the need for a box spring. This one is pretty inexpensive (around $100 for a king size with free shipping), and is also super easy to set up. (Update in 2020 – in the 4 years since this post was written, we have had no issues with squeaking or instability from this bed frame and our son’s room now has one too.)
Metal platform for king size mattress.
What Hannah lost in floor space in her room with the bigger bed, she made up in under-the-bed storage!!


Place a rubber non-skid rug pad on top of the metal platform before adding a bedskirt and mattresses. Initially I placed the bedskirt right on top of this frame, but we soon realized the bedskirt on top of the metal is too slippery – after the “new” bed was slept on, the mattresses would slide a few inches away from the headboard!

I took the mattresses and bedskirt off, placed the rug pad on top of the platform, THEN added the bedskirt and put the mattresses back on. I used a 6’x9′ rug pad and just cut it to fit after it was on the platform. The rug pad has worked great, no more mattress trying to escape onto the floor!!

Two twin size beds converted to a king.

Fill the gap between the two twin mattresses with a foam bed bridge. This was the part that made me hesitant about converting two twins to a king. How could this be comfortable??? After reading lots of reviews I bought this one, and honestly, it is not going to make the top of your bed completely seamless but it fills the gap pretty well. It does create a very mild raised area in the middle of the bed but it’s not uncomfortable. Here are a few opinions on it:

  • Hannah does not sleep directly in the middle of the bed but does sleep with her legs and arms kind of flayed all over the bed, and the foam filler doesn’t bother her at all. She loves her bed!
  • Hannah’s grandparents slept on this bed over Thanksgiving and didn’t even notice the filler.
  • Hannah’s aunt and uncle slept on this bed over Christmas and they said the filler was just fine.
Maybe our guests are just being nice (but I doubt it because my favorite father-in law did admit the mattress was VERY firm so I think they would tell me 🙂 ) but Hannah has spent many MANY hours sleeping on it and does not find the bed bridge to be uncomfortable or an issue in any way, especially when used in conjunction with my next tip.
Foam bed bridge fills in gap between two twin mattresses and converts them to a king.
Foam bridge fills the gap between two twins when converting them to a king size bed.

I strongly suggest investing in a pillow top mattress pad. You may recall my post for Project Design on How To Make A Beautiful Bed where I shared my love for our thick “mattress enhancer”. It gave new life to our older mattress so I figured it might help disguise the bed bridge, and it seems to be doing the trick!

Also, see how the sides of the mattress pad are not taut? That is because of that 5″ difference in a true king to 2 regular twin mattresses. With the thick pillow top mattress pad, king size sheets fit perfectly on the mattresses without having too much slack, so the thick pad does double duty – makes the bed more comfy AND helps the sheets fit better (you don’t have to get extra deep fitted sheets).

Mattress enhancer disguises gap between two twins converted to a king.


Since regular mattresses are 5″ shorter in length than the platform underneath, there will be a gap either at the head or foot of the bed. I pulled the mattresses all the way down to the end and then filled in this gap between the bed and the wall with a DIY upholstered headboard

Two twin xl mattresses make up a king size bed
two twins beds converted to a king
The custom headboard I made fits right under Hannah’s huge bulletin board that I installed spruced up Ikea lights on, and Hannah covered with all her favorite photos for a big statement art piece.

Read more about how to DIY a headboard here.  There are also tons of affordable upholstered headboards on the market that can be attached to the wall behind the mattress and fill in this gap perfectly. The headboard is a great solution to filling the gap and is comfy to prop up against for studying. Or reading. Or Netflix marathons 🙂

A quick recap on how to transform two twin mattresses into a king!

• Set up a king size platform bed frame

• Cover the top of the metal bed frame with a non-slip rug pad

• Place bedskirt over rug pad

• Place the twin mattresses on platform

• Use a foam bed bridge to fill the gap between the mattresses

• Cover both mattresses with a king size mattress enhancer

• Compensate for the short length of the mattresses with a DIYed or purchased upholstered headboard.

• Finally, finish off the supersized mattress with comfy bedding and then enjoy your huge new bed!
The ruched Mirabel duvet from Crane & Canopy.

how to make two twin mattresses one fantastic, cozy king sized bed! 

My little sleep-loving chick was so excited about her new bed!!!!!!!!!!
Fifteen with a king sized bed to slumber on! What a life!
(and a bed bigger than her brother’s – an added bonus!)
The day I got it all set up….

I hope this post answers any questions you might have about converting two twins to a king. Here are the sources I referenced in this post all in one spot! 


Bed platform 

Non slip rug pad 

Bed bridge (foam filler for between mattresses)
Mattress enhancer (pillow top mattress pad)
Wall color:  Benjamin Moore Splash 2059-60

Have a great day!


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Wednesday 30th of June 2021



Monday 19th of July 2021

Thank you so much Nancy!


Monday 14th of June 2021

Thanks for all the ideas! Especially the mattress bridge. Can’t wait to get rid of our giant, heavy king mattress and replace with two twin XLs. - Sam


Monday 19th of July 2021

Glad you found this post useful Sam!


Saturday 17th of April 2021

Thank you so much!!!! So very helpful...and creative on your part!! 🙌

Alicia Wagner

Tuesday 27th of October 2020

Hi! We are purchasing a second home and want the ability to switch between a king and two single beds depending on our guests. Is this something that can be easily switched out now and again? Thank you!


Friday 1st of January 2021

You will need two twin bed bases rather than one king, but yes, it would be easy to convert to two beds!

Holly Stone

Monday 28th of September 2020

Awesome!!! Thank you SOOO much for tips!!


Friday 1st of January 2021

You're welcome Holly! Glad they can be of some help to you!