How to Make a Fitted Sheet from a Flat Sheet

Learn how to make a fitted bed sheet from a flat bed sheet with this tutorial.  

Do you get tears or holes in your fitted sheets but the flat sheets are still usable?  We do!  

We had two sets of the same sheets and the fitted sheet ripped on both sets.  To get more use out of these sheets, I converted one of the flat sheets into a fitted sheet and now the set can be used.

Converting a flat to a fitted sheet will work with any flat sheet and the sheet can be converted to a fitted sheet for the same size bed.  I will mix and match different sheet sets together to get more use out of them.

Click the link below to watch our full video tutorial on YouTube or keep reading this article for a photo tutorial.

WHAT YOU NEED to make a fitted sheet from a flat sheet

Look at the end of this tutorial for more links to products needed for this project.

• Flat Sheet
• 1" Wide Elastic
• Sewing Machine
• Thread
• Ruler, Cutting Mat & Rotary Cutter or Ruler & Scissors
• Large Square Quilting Ruler (optional)
• Seam Ripper

INSTRUCTIONS to make fitted sheets from flat sheets

STEP 1: Measure the mattress

The first step is to measure your mattress. A flat sheet that fits on the mattress can be changed into a fitted sheet for the same size bed.

I have a full-size flat sheet, so I’ll change it into a full-size fitted sheet.

Mattress sizes vary, so to be sure the sheet will fit the bed correctly, measure the length, width and depth of the mattress. 

My mattress is 53” Wide, 75” long and 7” deep.

STEP 2: Calculate The Size to cut the sheet

Next, calculate the size of the flat sheet needed to make the fitted sheet.

To get the width, take the mattress width and add the Depth x 2 and then add an extra 5”.

So for my bed, that’s 53” + (7” x 2) + 5” = 72”

For the Length, do the same calculation but use the mattress length.

So my calculation is 75” + (7” x 2) + 5” = 94”

STEP 3: Prepare the Flat Sheet for cutting

Cut the flat sheet to the measurements calculated for width and length.

If the flat sheet is not large enough, use a seam ripper to carefully remove the stitching holding the top and side seams.  My sheet did not have enough length without removing the top folded over fabric.

Remove the edge and top seams as necessary so the sheet is larger than the size to be cut.

Lay the sheet on an ironing board and iron the sheet flat opening all seams.

STEP 4: Cut the Flat Sheet to size

Cut the flat sheet width and height to the size calculated in step 2.

After measuring my sheet width, I need to remove 4" from both sides of the sheet.  So, I folded my sheet in half with the two sides together.  Then I folded the sheet bringing the bottom to the top a couple of times until it fit on my cutting mat.  So, I had quite a few layers.

The edge on the right side of the photo is the left and right sides of the sheet.  I lined up the raw edges on all of the layers.  Using my ruler and rotary cutter, I cut off 4" of the sides.

Calculate the amount to cut off the height of the sheet. Rotate the sheet and cut off the extra so the height equals the calculated height in step 2.

When cutting off the sides and top/bottom, cut off as much of the unfolded edges as you can.  Since this fabric was folded over before, it may be weaker than the other areas of the sheet, so if you can, cut those sections off.

If you don't have a rotary cutter and mat, measure, mark and then cut off the sides and the top/bottom with scissors.

STEP 5: Cut out the Corners

To create the fitted corners, cut out a square from each corner of the sheet. The corners will each be sewn with a French seam to have a fully finished edge and create the pocket for each corner.

Fold the sheet into fourths with the four corners together.

The size of the square to cut out of the corners will be the mattress depth measurement + 3”.  So, for my bed the calculation is 7” + 3” = 10” square.

Use a large square quilting ruler to measure and cut the four corners from the sheet.  I cut all four corners at once by folding the sheet into fourths with the four corners together and using a square quilting ruler and rotary cutter. 

If you do not have a square quilting ruler and rotary cutter, use a ruler to measure and mark the four corners and then cut the corners with scissors.

STEP 6: Sew the Pocket Corners

The pocket corners should have a finished seam on both sides or the fabric will fray during washing.  An easy-to-sew seam is a French seam and this seam produces a seam with no raw edges on both sides.

Thread the sewing machine with a thread color matching the sheet color in the top and bobbin.  Set the machine to a straight stitch at the normal length and have a standard presser foot installed.

To make a French seam, start by folding the two sides of one corner together with the WRONG sides together.  Pin along the seam to hold it in place.

Sew a 1/4" seam starting at the fold and ending at the edge of the fabric. 

Turn the seam so the wrong side is facing out and the RIGHT sides are together. The seam and raw edge are now on the inside.  Iron the seam flat. 

Next, stitch a 3/8" seam along the same seam again from the folded corner to the edge.  This will encase the raw edges in the seam allowance and finish the French seam.

The first corner is complete and the seam is finished with no raw edges.  The photo below shows the right side of the finished seam.

And the photo below shows the inside of the seam and there are no raw edges on either side.

Continue and sew the other three corners in the same way.  

STEP 7: Measure and Cut Elastic

I prefer to have elastic around the entire perimeter of the fitted sheet.  It helps to hold the sheet onto the bed.

Place a pin by one corner of the sheet and use a tape measure or other ruler to measure around the perimeter of the sheet along the raw edge.  The pin helps you to know when you've measured around the entire sheet.

Calculate the length of the elastic to cut.  Take the perimeter measurement divided by 2 and then add 2".  My measurement around the sheet was 249". So, my calculation is 249" / 2 = 124.5" and then add 2" to get 126.5".  I rounded it up to 127".

Measure and cut the length of elastic you need for your sheet.

Use a 1" elastic around the perimeter of the sheet.  I have this buttonhole elastic left over from another project to use. 

STEP 8: Pin the Elastic to Sheet

The elastic will need to be stretched as it's sewn to the sheet.  To make it easier to ensure the elastic is evenly spaced around the sheet, I recommend pinning it in quadrants.

So, place three quadrant pins in the elastic.  Fold the elastic in half and place a pin in the middle of the length. 

Then fold the elastic again placing the pin and the ends together.  Place two pins at the fold on each half of the elastic. This marks the four quadrants of the elastic.  

Next, fold the sheet in half and place two pins to mark the halves.  Then bring those two pins together and fold the sheet to get the four quadrants and mark those with the pins.

Pin the elastic to the RIGHT SIDE of the sheet matching up the four quadrant pins on the sheet and elastic.  There will be twice as much sheet fabric than elastic.  Start/end the elastic along one of the sides by matching up a pin and the end of the elastic.  The two ends of the elastic should overlap by 1”.

Line up the raw edge of the fabric halfway across the elastic and pin it in place.  Place the elastic on the right side of the fabric.

Pin all four quadrants by matching up the pins in the elastic and the pins in the sheet.  Make sure the elastic is flat and not twisted.

Once you have the four quadrants pinned.  Pin again in the middle of each quadrant.  Fold the elastic in half by bringing the two pins at the ends of the quadrant together and then finding the middle.  Place a pin in the middle.

Fold the sheet fabric together and mark the middle in the same way.  Bring the elastic center and sheet center pin together and pin the elastic and sheet together.

Depending on the size of your sheet, you may need to add more pins.

STEP 9: Sew the Elastic to the Sheet

Next, sew the elastic to the sheet.  Have the elastic side facing down and the sheet on top of the elastic with the raw edge lined up in the center of the elastic.

Start at one pin, stitch a few stitches forward and back tack.  Then start stitching forward but fully stretch the elastic between the two pins so that the sheet fabric is flat on the elastic.  As you stitch, keep stretching the elastic by holding the fabric behind the presser foot and pulling the front.

Stitch on the sheet fabric until the next pin.  Then stretch the next section and stitch.  Keep stitching around the entire sheet.

The elastic will gather the sheet!

STEP 10: Sew along the edges of the elastic

Fold the elastic towards the WRONG side of the sheet.  The elastic will cover the raw edge of the sheet.  A bit of the sheet fabric should extend past the elastic on the right side as shown in the photo below.

Stitch around the sheet along the outer edge of the elastic.  Stretch the elastic as you stitch so that the sheet is flat. 

Finally, stitch around the other side of the elastic in the same way stretching the elastic as you stitch.

The flat-to-fitted sheet is finished!  The photo below shows the three lines of stitching on the elastic.  The raw edge is encased in the elastic so it won't fray during the laundering of the sheet.

The outside of the sheet is nicely finished and gathered all the way around.

The new fitted sheet fits perfectly on the bed and is ready for use!

We hope you enjoyed learning how to make a fitted sheet from a flat sheet.

Some other mending tutorials are available below:

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• Replace Elastic in Pants - Don't you hate it when the elastic in your favorite pants gives out?  You can replace it!
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• How to mend a Sheet - Do you have a hole along the edge of your sheet.  Don't throw it away, mend it!
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• How To Sew On A Button by Hand
• How to Fix a Hole in a Field Bag and add a fabric lining
• How to Fix a Stained Shirt
• How To Sew On A Button With Sewing Machine
• DIY Big Board Ironing Board Cover
• How to Sew an Easy Ironing Board Cover (Free Pattern)