Last week I was asked about upsizing a garment and if it could be done. The answer of course is that it can, but how complex the job is going to be depends on the garment.
I thought I’d do a blog post on garment sizing and how you would think about increasing the size of a garment.
To start with you have to decide how many extra inches/cm you want to add. If it’s only a few the job will not be too hard but a significant size change will require a lot of calculation.
I’d also suggest checking your other dimensions. Do you want to add extra width to the neck and shoulders? What about the depth of the armhole?
Here is a very basic sketch of a sleeveless top so you can see the dimensions you’ll need to think about.
So how do you plan the size change?
If the biggest size given was 50″ chest diameter and you want 56″ you will have to add an extra 6″.
I’m going to then assume that you want to add half (3″) of those stitches to the front and half of that to the back. So your back/front width will be 56/2 = 28″.
This takes care of the body width for you, but what happens when you reach the armhole?
Next you need to decide the width of neck and shoulder you want. These numbers don’t change as much as the bust measurement so even if you are adding some width to the biggest size it won’t be very much.
So if the original neck width was 8″ and each shoulder was 3″ you would have the total back shoulder width of 8 + 3 + 3 = 14″
If you wanted to make that 8 1/2″ and 3 1/2″ your back shoulder width would be 15 1/2″.
So at our armhole we will want to decrease from a body width of 28″ to a back shoulder width of 15 1/2″.
Look at the schematic and you can see that this happens at both sides. So we will calculate that decrease: 28-15 1/2 = 12 1/2″. Half of this is: 6 1/4″ which is the armhole decrease inches at each side.
Now that you have all the numbers you convert them all to stitches with your stitch gauge.
If you have 5 stitches for every 1″:
Front/back extra stitches: 3″ x 5 stitches = 15 extra stitches front and back.
Armhole decrease stitches: 6 1/4″ x 5 stitches = 31 stitches decreased at armhole each side.
Next question, how will you decrease those stitches?
I’d suggest examining the pattern. You will see that you will have initial stitches bound off at the bottom of the armhole and then stitches decreases as you work up the armhole. See how many extra stitches you will have to decrease to get the back shoulder width you want and distribute them within the pattern. In other words, if 10 stitches are bound off then perhaps make that 12-14 and then keep decreasing the remainder as in the pattern until you have the width you need.
I bet it’s easy to see my engineering background coming out when I talk about numbers right?!