While waiting for the 1 yard of merino wool to arrive, I have been turning my attention towards converting my prefolds to fitteds. I have now tried two variations on this theme.
After tons of research I found a few tutorials that took me in the right direction. I first tried with my premium prefolds (4x8x4 layers / 14.5" x 21" unwashed) but I have to alter my pattern a bit to make it work better. With my regular prefolds (4x6x4 layers / 14.5" x 21" unwashed) I have made a fitted diaper that fits my 13-month-old fairly well. (He is small for is age, so this would probably fit 8-12 month olds as well).
So, I give credit to
Shanna for the original idea, and here is my tutorial - with a few alterations that are useful if you want to make a fitted diaper from a prefold.
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You want your prefold to be washed a few times (not brand new)... The dimensions of this prefold are 12.5" x 17" WASHED.
Here I decided to go ahead and slightly iron the diaper so that I don't have bunching issues when I get to sewing. Fold the prefold lengthwise and make sure that the inner seams line up as well as the edges.

Make yourself a pattern. Trace around all sides of the folded prefold (my pattern is about 17" long and 7.25" wide). Mark where the seam is with a dotted line. Then measure 1 inch from the seam toward the edges. This will be your fold line. Then make the tab lines (I made my back tab about 3" wide and the front tab 3.25" wide). There are two ways to do this. In the example below I decided I wanted the advantage of having more elasticity. So I made my line cut straight to the fold line and only just before the fold line made the curve. I like this better than doing a more gradual curve because I found that even though the gradual curve will cover the bum up better you may end up with bigger gaps where things could leak out... (By the way, the purple line on the pattern is a mistake of mine, please disregard).

Trace the lines you want to cut with a fabric pen.

Make the cut (BUT ONLY TO THE FOLD LINE, not any further - and do not cut down the fold line).

Open up the cut, you will find a bit of left over fabric from the layers in the middle. Trim this extra back to the seam line.

You just have to do this for the mid section, not for the tabs of the diaper.

Now find the seams, one of the seams will be a bit jutted out. It is folded over instead of sewn through. Kind of hard to see in this picture. This will be on the INSIDE of your diaper.

Take a seam ripper and break the threads. Try not to damage the diaper too much, and don't go all the way through, you are just making a casting for your back elastic. Do this just below the surge line of the prefold at the back (if you made a more gradual cutout for the back there will be a difference between back and front).

So the same at the other seam at the top back, but this one is not folded over, so you are going to have to cut a few layers of the diaper slightly.

Here is a nifty trick! Put a small saftey pin on the end of your elastic. Then slide the point of a knitting needle or a BBQ skewer into the clasp of the saftey pin. Then just slide the elastic accross to the other hold in the diaper. If you didn't make a deep enough cut you will have to go back and cut again.


Use a zigzag stitch to hold the elastic in place. Go over the area several times making sure that you also catch any raw edges you made in the diaper - to prevent it from developing holes later on.

Pull the elastic tight, so that it still has a tad bit of stretch, but also so that the fabric of the diapier gathers up. Attach the other end of the elastic to the diaper with a zigzag. Again making sure you sew up any cuts. Put the ends of the elastic tight and snip right at the seam, this way it will not show.

Now you are going to fold the flaps over to the OUTSIDE of the diaper (not the side you were just attaching the elastic to.

Make sure that you have about a 1/4" "roll over" from the edge of the leg opening. (The cut V you see in the picture below is not folded directly on the point of the V, it is folded in another 1/4".) This will be handy later when you are sewing up the raw edges - it will make for a much neater edge.

Pin the edges so they won't shift around.

Keeping that 1/4" edge rollover, pull the two edges of the flaps together and measure your seam allowance. Here I will have a 1/2" seam allowance, this can be different for different types / brands of prefolds.

Sew the flaps together with a straight stitch, using the measured seam allowance.

Lay out flat and cut any extras.

Put your hand through the tube, grab the end and pull through.

This is what you should end up with.

Change back to a zigzag stitch, and tack down the rounded edge of the soaker. Start sewing about 1/2" away from the edge (you need to put elastic in the edge, so you don't want to sew up that opening).

When you come to the other edge, turn and use a straight stitch to make a casting for the elastic down this leg. When you come to the end turn and switch again to zigzag. Sew around the soaker and then back down the other leg with a straight stitch again.

This diaper measures about 5" accross the soaker, from one seam to the other. This could vary for your baby...

This is what the diaper should look like now.

Using our nifty trick, push the elastic through one of the legs castings. Don't cut the elastic until it is completely tacked down.


Now you want to turn in the raw edges on the diaper tabs. If you open up the fold this is pretty easy. Just roll in about 3/8." Pins make it easier.

Pin both edges together and sew close to the edge with a straight stitch.

When you get close to the elastic, switch to a zigzag stitch, to make sure that you catch all raw edges that cannot be turned in.

Continue sewing right over the edge of the casting, catching the elastic. Go back and forth several times, making sure the elastic is secured.

This is what you should end up with, a nice neat edge, with no raw cut edges sticking out.

Repeat turning in the raw edges and tacking down the elastic for the other end. Now you can pull the elastic tight and cut right at at the line where it was secured.
Repeat for other leg/side.

To make sure nothing is going to ravel away later, I like to go over the very edge of the soaker once more before finishing.

Secure with pins or a snappi, or you could get fancy and secure with snaps or velcro. I would recommend fitting it on your baby first and also allowing for growth... adding more snaps/velcro where they might be needed later.

Side view.

Bum view!

Comments much appreciated! I would love to hear how it works out for you or if you have any suggestions! :)