Too big dress? Learn how to shorten straps & take in side seams

Do you have a dress or tank top that is too big? In this tutorial, I will show you how to change the length of any strap on clothing, as well as taking in the side seams from the underarm, and going down as far as needed, to alter a garment to fit you perfectly. 

This is an easy DIY clothing alteration perfect for those last-minute quick fixes on for example prom or bridesmaid dresses where you often will need to shorten the shoulder straps and sometimes also the side seams for a perfect fit. In this tutorial, I show you how to alter both.

This tutorial is part of my Mend with Matti-series where I teach you how you also can repair and make your own alterations to clothes that you already have so that you can love and use your garments for longer. Check out other mending-tutorials here.

The dress I am altering today is so beautiful and it was also a really great find as I got it from a clothes swap. My friend who owned the dress previously is one size bigger than me, but even if she wasn’t the dress might have needed to be altered anyway as dresses often are too big for me in the bust area if I want them also to fit me comfortably around the hips. 

I know I am not the only one with this issue – but luckily this is a really easy tutorial on how you can amend your garments to fit you better.

Without further ado let’s get into the tutorial!

Step 1: Try it on!

First I started by trying on the dress and estimated how much I needed to take in the side seams and the straps. This step is easier if you have someone who can pin it in place for you, but if you are like me and you are on your own take off the dress/tank top and pin as much as you estimated. Then try the dress on again and make sure it’s a good fit.

Once you are satisfied with the fit take note of how much you would like to take in and then take off the dress or tank to get started!

How to shorten the straps

Before taking off the pins, place another pin in the top layer ONLY on the strap, then un-pin the other pin holding two parts of the strap together.

If your dress is lined, or like mine where the seam edges are hidden inside a binding, it’s now time to unpick the stitches holding the strap together.

Remove the old strap, mark where the strap was placed at the garment and pull the strap in place, pin it, and stitch in place.

When stitching the strap in place stitch where it was previously attached and then make sure to securely stitch the strap in place by going back and forth a few times on your machine.

Now cut off the straps!

If your garment is lined I will suggest you to re-attach the lining by hand stitching using slip stitches. If you, like me, have binding keep on reading, and if you have neither please consider yourself done! If so once you cut off the straps and your fabric is fraying a lot I would either whip stitch the ends or use fray check – or both depending on the situation.

If you have a binding like me do the following steps:

First, you need to stitch the seam that holds the binding and dress together on the edge. These stitches will, later on, be hidden inside the binding as such you need to unfold the binding to finish the seam.
As my fabric is a bit slippery I’m making sure the straps and binding are laying correctly in place to avoid it to cause any pulling and creasing. Keep it in place with pins. Whilst sewing make sure that you start and finish in already existing stitching lines.

Now it’s time to do the topstitching: Fold the binding over make sure that it lays flat and pin in place. Start by stitching into the existing stitch of the topstitching. Fasten and start sewing, taking care to stitch as straight and even as possible.

And the straps are now attached!

How to take in the side seams

Now it’s time to take in the side seams. Using the measurements you wrote down earlier and measure out how much you will take in the side seams then pin in place.

I first tried to use a chalk marker and just estimate how far down I would alter the side seam. But it was hard making it look even on both sides using this method so instead, I went for a more accurate method using a ruler. This enabled me not only to go equally far down the side seams but also to also mark a straighter line on each side.

Once the fabric is marked with a chalk marker/fabric marker make sure to pin along the line. As my fabric is very slippery I decided to baste stitch along the marked line using a contrasting thread. If you have a less slippery fabric you may skip this step. I basted it using a 5.0 mm stitch length so it will be easy to unpick later.

After I baste stitched both sides it’s was time to unpick the binding. Once un-picked it’s time to stitch along the marked line/basting stitches. If you have binding like me – make sure the binding is pinned to the side so you will not sew into the binding by mistake.

You can stitch with any seam you think would suit your garment using a regular sewing machine. Even if the stitching on my dress was done by a serger I decided to instead of dusting off my serger and re-thread it for such a short seam, I could use a hem stitch on my machine. The hemstitch does both a seam as well as hemming the edge of the fabric at the same time.

Sadly, the stitch I used pulled on the fabric a bit in a way that I didn’t think looked very neat and professional. As such, I tried to flatten it out a bit with my nails. I also pressed the seams with an iron to create a more neat and professional finish.

Once you stitched the side seams in place cut carefully off the excess fabric as well as excess binding.

Now it’s time to reattach the binding again but first, we will need to give it a bit more space to work with so that I can stitch it on the machine, and I started to unpack the binding a bit more.

Before moving on to the next step I decided also to fray check the side seams we just cut to make sure that the fabric will fray as little as possible.

It was a bit fiddly to get the binding in place at the seam on the edge of the armhole. Even this seam will not be visible once the binding is folded in place I want to create as accurate stitching as possible for a neat finish. Once I finally got the binding into a nice neat position I pinned it in place.

Now it’s time to stitch the seam closest to the armhole starting and finishing in existing stitch lines. Once I stitched that in place I notice that I had to stitch 1/2 cm together at the top of the side seam otherwise it would be a gap just under the armhole. I finished off the seams on both sides and then cut off any remaining excess binding.

Now it’s time to fold the binding over and pin it in place. Make sure the edges on the binding are separated to avoid bulk and also make sure the edges are inside binding and not poking out (easier said than done😅).

Then topstitch binding in place and repeat on the other side.

Now it’s finished it’s far from perfect but it will do the job! Look how much better the straps fit as well! Now I can wear this dress without it feeling like I’m wearing a big tent and that’s amazing!

I hope this tutorial inspired you to take in some side seams, shorten straps, and generally just inspire you to alter clothes so that actually fit you better!

If you’re interested in more videos like this on mending, upcycling, or generally how to live an awesome and sustainable life. Make sure to subscribe to the Miss Matti Youtube-channel to make sure you do not miss any upcoming videos.

Also, if you did shorten your straps or alter the side seams, or both, on anything and make sure to tag me on Instagram @missmatti also used to hashtag #mendwithmatti as such I can see what you’ve been doing because I would love to see your projects.

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Leave me a comment down below and let me know what kind of video tutorials that you would like to see from me I would love to hear from you so leave a comment below and let me know!