Baby Onesie into Baby Gown Tutorial

One of our favorite early clothing items for our son was a baby gown… it made those middle of the night changes so much easier when they were brand new and you were so afraid to change them!  Today’s tutorial will be on how to take a regular onesie and turn it into a baby gown!  You will need the following supplies:

– Baby Onesie

– 3/4 yard of fabric

– 1.5 inch wide ribbon

– 1 inch wide elastic (about 17-18 inches)

– 1/4 inch wide elastic (about 14 inches)

I used an existing baby gown to get my estimated desired length of the gown.  Here is a photo of the gown I used as a base pattern next to my onesie and all of my supplies.

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Since my onesie was a size 3-6 months, I decided to make it a little bit longer than the 0-3 month gown that I already had on hand.  The gown on hand was 22 inches long, from top of the shoulder seams to the bottom hem.  I decided to make mine 23 inches long.

Take a water soluble pen and mark where you will connect your fabric to your gown.  I like to do this on front and back.  I measured my onesie and determined that I wanted about 5.5 inches from shoulder top to where my fabric would lay.  This is really your personal choice as to where you want your waistband to be.  Anywhere from 1-3 inches below the armpit of the onesie is just fine.

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When you mark your line, make sure to mark on the front and the back!  I always double check to ensure that they line up on the side seams for a nice straight line.

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Next you will want to cut your fabric bottom.  The best way to gauge the width of the fabric cut is to stretch your onesie and measure how wide it will go.  This onesie stretched to about 15 inches wide, so I made a fabric cut about 14.5 inches wide.  To get your length of your fabric piece, simply subtract your shoulder to drawn line amount (5.5 inches in this case) from the overall desired length.  I then ADD 1 inch back into that to allow for the bottom hem with elastic.  If you are doing an open gown or a “skirt” onesie, you won’t need to add back on the 1 inch.

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There is the fabric piece and the onesie- pretty simple up to this point!

The next step is to sew the back seam of your gown fabric.  I didn’t want to use my serger for this seam, so I sewed a french seam.  That is a seam where you sew the fabric wrong sides together first, THEN you trim and sew it right sides together.  It makes a wonderfully cased seam that has NO threads sticking out.

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I serged the top and the bottom of the gown fabric.  Then, I pressed the onesie in half to get a marker as to where the back seam should line up.  I also pressed the gown fabric so that I had two pressed side marks where the gown should match up to the side seams of the onesie.

I pinned the gown back to the center back of the onesie and then matched up the side seams.  Because the top of the gown fabric  was serged and it was going to be covered by ribbon, I sewed the fabric as it would show on the gown.  You can also sew them right sides together and press the gown fabric down after.  It is your choice.

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To sew the gown fabric to the onesie, I then slid the onsise up over my free arm of my machine.  I then stretched the onesie to fit the gown fabric and stitched a straight seam, about 3/8 of an inch seam allowance down.

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It was now time to put my ribbon casing on the gown.  I heat sealed both ends of the ribbon and then pinned it at the start point (the center back seam) I eyeballed the placement of the ribbon- the goal was to have half of the gown fabric covered and half of the onesie fabric covered. Again, I stretched the onesie to make the ribbon sew flush against the knit fabric.

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When it came time to overlap the ribbon, I stopped just short of that seam.  I then sewed the bottom casing.  About 1 inch of ribbon was left “free” for overlap, and also allowed me to insert my elastic into the casing.

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I then fed my elastic through this casing- again, depending on the SIZE of the onesie, your elastic may be longer or shorter.  It is your choice.

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I overlapped the elastic by about an inch, and then zigzag stitched the elastic so it was nice and flat.  This helps it to lay neatly in the waistband casing.

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I then finished the ribbon overlap and stitched the top, bottom and the side to seal off the casing.  This also helps to hold the elastic in place.

For the hem, I simply ironed up a half inch casing for the elastic and stitched it- leaving about 1 inch open to feed the elastic through.  Overlap the elastic at the bottom the same way you to the waistband elastic and zig zag stitch.  For a different look you can use bias tape to create an elastic casing about 1.5 inches up from a finished bottom- it will give the appearance of ruffles on the bottom.

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Sew your bottom casing shut when you’re finished zig zagging the elastic and that is it!  Your gown is now complete!

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All in all, an easy 30 -60 minute project that is a wonderful gift for that new baby!

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  1. Essie ostland says:

    The instructions were very well done . I am excited about making some of these for my new granddaughter and I plan to make a similar dress for her big sister. For that I will use a Tshirt with the matching fabric.

    1. Thanks!! I’ve also used knit tank tops to make tank dresses- it works well, and you can use elastic thread in your bobbin to shirr the cotton skirt to the knit top.. it turns out really cute and is a quick project.

  2. Jean Adams says:

    How would u determine yardage for fabric for larger onesies.

    1. Hi Jean! I apologize for the delay in my response. For the yardage of the gown, you can adjust as needed width wise by allowing a 4 to 1 ratio or even a little more if you want- for instance, I will place my onesie on the selvedge, and make the piece of fabric 4 times as wide as that onesie…. if you want a lot of gathers I would say 6 times as wide. I hope this helps with different sizes!

  3. Carol says:

    Wonderful tutorial! Been looking for one for a few months, and this one finally makes sense! Thanks!

  4. Cindy Miller says:

    I’m so excited to try this! First grand was a darling boy and he’s been so much fun to shop for. But I’m SSSOOO ready to “Get Girly” with this one due in May! Your instructions are so easy to follow and the pictures help as well.
    Thanks so much, Cindy (Grandy)

    1. Congrats on the upcoming arrival of your Girly Grand in May! I’ve been having a blast making things for my little girl, who arrived in NOV – including LOTS of big bows!

  5. Alisha Bynum says:

    I’m going to try this this weekend. Thanks for much for the great tutorial!

  6. Susie Bunch says:

    Very nice! I have foster babies and love making special clothes for these precious babies all the time.

  7. Marie says:

    After the ruffled skirt is all sewn, how do you attach it g to the onesie without the onesie getting all twisted?
    Also how do you keep from sewing the back of the onesie to the front of the onesie.? I am having great difficulty seeing the 2 parts together

    1. Hi Marie- I pin the skirt to the onesie (snap crotch open so its just one big tube of knit!) and then slide the pinned onesie and fabric over the free arm of my sewing machine. If you’re going to use a serger to finish off the cotton part or attach to the onesie, you will need to cut off the bottom of the onesie OR you can fold it so that the snaps are up by the shoulders and attach that way- basically it would be wrong sides together of the onesie fabric and right sides together of the cotton fabric and the outside of the onesie where you’re attaching the skirt. (You’ll lose maybe 1/2 inch of onesie length but will be able to keep the snap crotch if you wanted that option)

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