How To Upsize Fitted Shirt Easy [Tutorial]

by Mariana Kirova

How to upsize a shirt - main

Lets face it. We all keep in our wardrobes some favourite garments that don’t fit us anymore. We love them so much that just can’t let them go and donate to a charity, for example.

With this tutorial you will be not just able to keep some of them longer, but also to wear and enjoy them again! 5 easy steps will show you how to upsize your favourite shirt and change it up to 3 sizes.

How to upsize a shirt - tools&materialsTools & Materials:
  • 3/4 or long sleeve fitted shirt;
  • Tape measure;
  • Seam ripper, thread snips or small scissors;
  • Corresponding colour thread;
  • Basic sewing tools;
  • Sewing machine.


Step 1: Unstitch The Sleeves

The easiest, but also the trickiest step. Be careful when unstitching the main armhole seam and the overlocking seam.

You also may prefer to just cut the sleeves around the seams. Go and do it – that’s the fastest way, for sure! Just do it carefully, close to both sides of the seam.


Step 2: Measure And Cut The Side Extensions

How to upsize a shirt easy - step 2The current upsize of fitted shirt is done by using the sleeves of the same garment. That allows to keep the clean design look with the same fabric and colour. The shirt is 95% cotton and 3% elastane woven fabric, which was really nice material to work with.

According to the standards of the garment sizing, we have to add 5cm for each size up – horizontally to each of the horizontal body lines: bust, waist and hips. Hence, if you want to upsize with 2 sizes (without adding extra room to the garment) – measure 5cm wide strip from each sleeve to add on both side seams.

So there are two things to consider here:

  • How much you want to extend the garment;
  • Do you want to add any additional room to the shirt.

If the garment has tight fit in general, as the shirt of this project, add another 1 – 1.5cm on each side (overall not more than 3cm). This way you will keep the fitted look, but also you will have a better comfortable feel when wearing after this upsize of fitted shirt.

I suggest you leave the extensions longer at the armhole. This is an easier way in which you can cut accurately and reshape the armhole later.

In terms of garment grading, enlarging a garment should be done horizontally (as it is done here), but also vertically on the garment. So, theoretically speaking, when grading one size up we also have to add 1cm vertically (from neck to hip). If you want, you can extend the length at the hem by adding a strip of garment or lace, for example.

This size chart refers to international sizing used in other countries than Australia. Sizes for fuller figure generally follow similar grading rules. However, if you are dealing with that sort of case, then try on the garment and do necessary adjustments, as human body changes differently in this size range.

Whatever the size, you only need to measure how much to extend (to add horizontally or also vertically to the length) and if there’s a need to adjust the armhole (by cutting under the armpit it to make it  bigger).

Step 3: Sew The Extensions

How-to-upsize-a-shirt-easy-step-3After checking all the measurements it is time to attach the side extensions to the garment.

You can see my shirt had additional button-up feature which I really liked and decide to incorporate in the design.

Depending on your dress shirt, your imagination and taste preferences you can work out to add something interesting too.

The sleeve may have a cuff you want to use, or it has hem embellishment – consider keeping it, it may add uniqueness to your work;).

TIP #1

TIP #2

It is a good time-saver if you use the sleeve hem. However, if you choose to cut, then consider sewing the hem before adding the extension. Will be easier because you will have both hems – of the garment and of the extension already finished.

Choose the attaching seam accordingly to the others on the shirt. In my case I attached the extension with a flat felled seam to match the overall look.


Step 4: Adjust The Armhole

How to upsize a shirt easy - step 4 - step 3Now you can shape the armhole curve and cut.

When reworking from garment with sleeves to sleeveless one, the armhole needs to be smaller (reducing circumference of the armhole) and more “open” (the armhole may need to be cut dropped).
All this is optional. I’d suggest you cut the sleeve curve and then – try on the shirt. If there’s a need, do the adjustments after.

In most cases the extra room under the arm will have to be reduced. Usually garments with sleeves have more room compared to sleeveless ones. Nevertheless, if the shirt is fitted tight on the body, might not need taking in yet lowering the hole.

If you still have to reduce the room under the arm, the easiest way is after sewing the sides extensions and cutting the curve. I did small darts under the arm on each extension.

My dart measurements are 1cm wide and 7cm long, however, yours will be different! So don’t follow this numbers, but check and measure your project. Sew the darts only when you are sure you have the correct numbers.


If you are confident in your garment construction you may decide to cut and reshape before attaching the extensions. You can either reduce from the back and front pieces of the shirt or from the extension you are going to add. However, do that only if you feel very comfortable and confident with your calculations.


Step 5: Finish With Binding The Armhole

How-to-upsize-a-shirt-easy-4For the binding you can use fabric strips from the sleeves or add different fabric. I decided not just to upsize the shirt but to change the design as well. Therefore, I’ve used another fabric for the binding.


Source your binding second hand. When in a charity shop have a look in the haberdashery section, it is always great joy to find useful bits and pieces there. Sometimes you can find ready-to-use binding attachments still in their pack and ready to use. With time you’ll gather different widths and colours, so you’ll never run out from this handy trim.


The Final Look

Upsize-fitted-shirt Refashioned-shirt-&-skirt-set

Along with the upsizing I did refashion the shirt as well. It was time to change this one colour design to something more exciting!

Even more. I combined the shirt with a skirt (which fabric I used to enhance the shirt) and created a whole new set. This article shows all the design details done on both garments.

I do hope, this upsize fitted shirt tutorial will inspire you for great sewing time! Eventually, what’s better if not bringing your faves back to life to enjoy them again?

Have good fun with such type of redo! If you feel like, share your thoughts in the comments below. I’m curious to hear your refashioning adventures.

Talk soon,










Mariana Kirova

Mariana is passionate about garment upcycling and helping others to make their own upcycled clothing. Graduated with Award in garment construction from WAIFT, Perth WA, Mariana is not a main stream eco fashion designer. She makes unique eco-friendly garments from unwanted clothes and materials and believes that small fashion professionals and DIY sewers can embrace sustainability in garment creation, thus changing the fashion world for good.

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