DIY Mermaid Halloween Costumes

I’m not the best at posting things when it’s seasonably appropriate to do so, so getting this post up in time for Halloween is a small victory for me.

Halloween is a funny thing for me. I’m all for dressing up and getting candy but I’m not at all a fan of the spooky/scary side of the holiday. Growing up, getting dressed up for Halloween was never given any sort of extra attention; I was left to find something around the house and make it work. I dressed up as a nerd many, many times because it required nothing special (mismatched outfit and tape on the glasses, yo). And I don’t think my family was unique in this approach.

More recently, it seems that everyone buys costumes, and I can’t say that I don’t see the appeal. Making costumes has no guarantee to turn out well and it often isn’t any cheaper than just going to the store and picking out a totally recognizable ___fill in the blank___ costume that your kid wants to be.

What’s your approach? Make? Buy? Tell your kids to go dig around the closets?

After buying my material this year I really debated this. Is it worth making costumes for my girls? Should I just buy our costumes like most the other moms?

But the fabric was already purchased, so I was locked in. No turning back. Lucky for me, this year, at least, I think the costumes turned out really cute.


Can you tell what these gals are supposed to be?

Haha, hopefully it’s not too hard to figure out. I asked Wendy what she wanted to be for Halloween, and I’m not going to lie, I definitely steered her answer a certain direction. The conversation went like this:

Me: You can be anything you want for Halloween. You could be a mermaid, or a princess, or a mermaid…

Wendy: I want to be a mermaid!

*Greta nods her head*

Wendy’s happy, Greta’s happy, mom’s happy. Win-win-win. I based my making process on this post from A Beautiful Mess.


We got our fabric from Joann’s (side note: someday, I’d like to plan ahead and buy my fabric from the SAS Fabric superstore in Phoenix-they have an amazing selection of costume/party dress fabric-but I just haven’t been in the dress up mindset when we’ve gone). I had planned to make the skirt with the cosplay fish scale fabric (like in the Beautiful Mess post) but our Joann’s wasn’t carrying it. So we looked around and found a shimmery ombre purple knit that would work nicely since it stretches, has some shine, and is one of Wendy’s favorite colors.


I’m not sure what kind of fabric the iridescent “fin” is (I don’t know why I think I can post about sewing projects without remembering to check the bolt for specifically what fabric this is! Goodness!), but it’s woven (not stretchy), it has purple undertones to match the skirt and it just seemed to fit the bill, so we got it. I also got teal and lavender tulle for under the fin to make it more full.


It might be considered risky, but I just winged it with this project. Winging it with kids’ projects is super awesome (not being sarcastic) because the stakes are so SO low. My 2 year old doesn’t care if the fit is perfect or if seams aren’t finished. And kids are so small that if you mess up, you probably have more fabric to fix the mistake or do a total remake, which is what I had to do with this particular project.

My original plan was to just have the fin at the bottom 4 inches of the skirt. Luckily, I had Wendy try on her skirt before I added the fin and I realized that this approach would definitely not work: she couldn’t walk at all! So I gave the skirt pattern a little more ease (I should have given it even more, though) and re-drafted to make the fin start at her knees. Eureka! Now she could walk! The skirts still turned out a bit tighter than I had intended, but Halloween is close so I think the girls will make it before experiencing a huge growth spurt.

A little more detail on the skirt construction: I measured the girls’ waists, added an inch for ease (should have added two inches, maybe more) and half an inch for seam allowance. I also measured from their waists to their knees as well as from their knees to the floor. For the main body of the skirt (waist to knees), I drew a rectangle where the top of the rectangle represents the waist and the bottom represents the knees, using the waist measurement+ease+seam allowance DIVIDED by 2. The side lines length should be the waist to knees measurement+whatever you need to add an elastic (mine was about 3 inches). I tapered the side seams in by about an inch on each side. I cut a long rectangle the length of the knees to floor measurement. I didn’t measure the width, but it can be roughly 1.5 to 2 times the width of your previous pattern piece. This piece was basted, gathered and made into a ruffle at the bottom of the main skirt piece. For the fin I cut three layers of fabric: 1 layer of random iridescent material, and two layers of tulle. Each of these was cut as a big circle, the inside of which should be roughly the circumference of the waist measurement and should extend out to length of the knee to floor measurement (guys, does this make sense? I don’t even know what I’m saying! Ha! I need to write more…and get better at math). I hand basted all the layers of the fin together and then sewed them directly onto the skirt, letting the seam allowance show from the right side of the garment.dsc_0424

We bought plain white long-sleeve (Halloween is never warm) shirts. I free handed a seashell pattern and used it cut out seashells from the purple knit fabric we used for our skirts. I used a heavy weight interfacing to fuse the shells to the shirts. And then, using a zigzag stitch and very short stitch length, I sewed around the seashells to make sure they stay in place on the shirt.

I spent about $30 total on material and shirts and probably could have spent just a little more on buying costumes. But the girls love their mermaid outfits, Greta looks particularly adorable walking around in hers (she kind of has to waddle in it), and I always love it when my Just-Go-With-It sewing projects end in success. In short: I have no regrets. At least, not this year…

In other news, we’re considering signing Wendy up for ANTM: America’s Next Toddler Model. If you haven’t noticed, she’s a natural. 😉



One thought on “DIY Mermaid Halloween Costumes

  1. So cute! We’re going homemade this year. We’ve done semi-homemade the last 2 years. I really hope Anthony’s costume looks like what I intended it to be….


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