How to Make Fitted Sheets From a Flat

I don’t know about you, but my kids refuse to use a flat sheet. I’ve tried off and on since they were about 2, but the flat sheet always ended up wedged to the foot end of the bed. So we only use a fitted sheet for their beds.

Kids will be kids. It’s always nice to have an extra sheet or 3. Today I’m going to share with you how I sew my own fitted sheets from a flat (or a piece of fabric).

This really came in handy when we made the custom bunks for the Winnie.  Since all 4 beds were odd sizes, I needed to custom fit all the sheets or deal with tucking lots of extra fabric under.  I hate tucking and readjusting sheets.  A mama’s got enough to do in my humble opinion.

Back to my fitted sheets…

My big kid’s mattress tops measure 27″ X 57″.  The mattress thickness is 4 inches.  You need to know all these measurements specifically for your own bed to fit the sheets properly.  I don’t want to get hate mail because you followed my measurements.  That and I doubt anyone has the same size bunks that we do.  We like to be different.

But given my bed size example, here is how you figure out the size of your fitted sheet.

Width of Sheet

  27 (width of the mattress)
8 (thickness of the mattress multiplied by 2)
+ 4 (for hem and overhang )
 39 inches

Length of Sheet

  57 (length of mattress)
   8 (thickness of mattress multiplied by 2)
+ 4 (for hem and overhang)
 69 inches

So you’ll want to take fabric or cut your sheets to the measurement that you find you need for your particular bed.

Cut Out Corners

Next you need to cut out notches so you can make your corners.  As I said, I have a 4 inch thick mattress and I have allowed for 2 extra inches on each side for the hem and under tuck (if that’s a word).  So I cut out a 6 inch square from each of the 4 corners of the piece of fabric.


Time to Hem

Now is the easiest time to hem your sheet. I tend to sew like a madwoman and go as fast as my machine will allow. I don’t want to have to fuss with any corners which is why I recommend sewing the corners together AFTER you have hemmed the edges.

I fold over my hem 1/4″ and then another 1/4″ and sew along the edge. I loathe pinning and have a dislike for the iron so I just do this turning under by hand as I go along with the sewing machine. It doesn’t need to be perfect.


Sew the Corners


Corners need to be sewed together next.  Simply line those cut out corners that are missing the 6″ squares and sew a 1/4″ seam from the point down to the edge.  Now you have a nifty corner for your sheet.


Attaching Elastic

In order to get the sheet to fit around your mattress, you need to attach elastic to the edge.

On the top of the sheet, I start on the left side about 8 or 9 inches from my corner seam and zig sag stitch a 1/4″ piece of elastic to the edge.  Once I’ve got the elastic attached with a couple of stitches at the beginning, I pull that elastic VERY tight as I let the machine pull the hem of the sheet through.  You just want the elastic pulled tight so it will scrunch the fabric and give you fitted corners.

I do the top of the sheet as one big strip and finish about 8 or 9 inches on the other side of the right corner.


And that is it.  So easy and it makes making beds a breeze.

I’d estimate that one sheet takes less than 10 minutes to sew custom fitted sheets from start to finish.  Worth the time in my book!

73 thoughts on “How to Make Fitted Sheets From a Flat”

  1. This worked out great. My husband has restless legs & his side of the fitted sheet always ends up with a worn tear so I buy more sheets & end up with a bunch of flat sheets & no fitted sheets. He now thinks I’m a genius. Perfect!

    • You are a genius Kelly!!

      (On a sidenote – I had restless legs at night and found that a good magnesium helped immensely!)

  2. I detest all twin sheets for bunk beds in RV. I gave it allot of thought and the method I came up with, I took a twin flat sheet and more less made a large pillowcase for the mattress. Measured the mattress and folded sheet over and sewed a seam across bottom and sides, turned inside out, left wide hem part as was and that’s the opening as for a pillow case, fits mattress great, no excess sheet to fight as well. I’ve only made one set , need to get busy and make an extra set.

  3. Thank you for your tips. I used your idea and made a cover for the cushions on my couch from an old flat sheet. Perfect the first time I tried and that rarely happens.

  4. I’ve been searching the web for easy to follow instructions on this. And you’ve provided! Thank you so much, and I’m excited to try this. We just bought a bunk bed and I have zero sheets! I hate walmart, and they’re the only place I’ve found that sells cheap sheets. This way, I can make my own with American made goods 🙂 woohoo!

  5. Hi, I am making fitted sheets from flat sheets for a friend. Her bed is 80″x80″x16″. The sheet is 92×108″. I can’t figure out what size to cut out for corners. Please help.

  6. How do you figure out the amount of elastic if you are stitching elastic all the way around? Twin? Queen? King?

    • Oh that is a GREAT idea! I have a tabletop ironing board for my heat press but it needs a better cover. Thank you Elizabeth!


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