A full tummy adjustment is a very common adjustment! How do you know if you need a full tummy adjustment? On a muslin, you will see drag lines pointing towards your belly. If you make a top according to your waist measurements and find the front is snug while the back is loose, and/or if your side seams pull to the front, these are indicators that a full tummy adjustment may help you with a better fit.
A full tummy simply means that your waist fullness is situated towards the front. For example, you may have a waist measurement of 46". In most patterns, that will distribute out to 23" for the front, and 23" to the back (or thereabouts). If you have more fullness in the front, your measurements might distribute something like 21" in the back, and 25" in the front. This is where you should consider sizing down so that the back fits properly, and then doing a full tummy adjustment for the extra necessary in the front. Tip: This adjustment can also work as a maternity adjustment!
If you would like to follow along with me in a video, you can watch the Full Tummy Adjustment on a Top/Dress over on YouTube.
First, we need to find our reference points. Start by marking the general area of the bust point (or chest point, depending on the pattern). This is generally an inch or so below the underarm, and more or less in line with the neck point. Again, this can vary widely depending on pattern type and features. You can always hold the pattern up against you and find the bust point that way. It doesn't need to be super accurate for this adjustment. Draw a vertical line from this point straight down to the hemline.
Next, we're going to draw two more lines. The first line is from the bust point to the side seam. Where these two lines intersect is one hinge. The second line is horizontally above the hem. You can do this a couple inches up from the hem for a top, or, if you are making a longer garment, aim this line about 6" down from the waist. Where the two lines intersect will be the second hinge.
Now, let's cut. The first cut will be the vertical line from the hemline up to the bust point. The second line will be from the side seam to the bust point. Cut to, but not through, to create the first hinge.
Next, cut the line from the side seam to the vertical line. Cut to, but not through, to create the second hinge. The last cut you will make at the center front to the vertical line. No hinge here, so cut all the way through. Just don't lose that little piece!
We're ready to make the adjustment. Remember that, because we are only working with half of the bodice, the adjustment you make will be doubled when you cut on the fold. Let's take our previous scenario of a 21" back waist, and a 25" front waist. You picked the size that would give you 21" both front a back, so 42" total. With your measurements, you will need 46" total. 46"- 42" = 46". You need to add a total of 4" to the front. Divided by 2 (only half the bodice), we will be making a 2" full tummy adjustment here.
Pivot the entire side seam section out and up, overlapping under the arm. You will add the necessary 2" space at the lower hinge (red mark). Place paper behind your pattern and tape the larger upper section in place.
When you added the width, you overlapped up under the arm at the side seam. This made the side seam shorter. In order to return it to its original length, pivot the bottom hem portion down by the same amount that you overlapped up above. This should bring the vertical line back to center for that section. Tape this section down as well.
Lastly, you will want to add some length to the center front. Generally speaking, you add 3/4" for every 1" adjustment, but it is always easier to try on the garment before hemming and take out length, rather than finding out you didn't add enough. Move the loose section down, keeping the center front vertical.
Only thing left to do now is to redraw the side seams and center front. For the hemline, gently curve from the side seam to center front. If you are making a longer garment and want to take some of the width out of the bottom of the hem, you can curve the side seam back in to where you want it.
That's all there is to it!
Happy Making!
Rachelle