This adjustment is for sewists for whom the shoulder seam length is correct, but for whom less fabric between the shoulder blades is needed for comfort. If you find that you have a lot of excess fabric or drag lines vertically down the back of your top, especially near the sleeves, then you may need a narrow back adjustment. Conversely, a broad back adjustment is especially helpful when the wearer feels restricted by their garment when reaching forward.
As an example of the need for a narrow back adjustment, I have a close friend who is a Twig + Tale® H-T size J when measuring her upper bust, and for whom the shoulder seam widths for that size are exact. Though she needs an FBA for the front, her back is very narrow and around 2” (5cm) of excess fabric has to be removed from the back to fit her correctly. I’ve removed this amount from the back of RTW swimwear for her in the past, and she routinely needs to do this to garment sewing projects of her own.
In adjustment order, you would look at doing this after checking for or doing a broad/narrow shoulder adjustment and a rounded upper back adjustment. Some people will find they need a combination of adjustments, and for some they may seem competing. For example, you may need both a broad shoulder and a narrow back adjustment, or vice versa. Everyone’s body is different, and being able to customise your clothing to fit you well is one of the great advantages and joys of sewing.
- Front and Back pattern pieces (we're demonstrating with the Grove Coat)
- A Toile/Muslin
- Tape Measure
- Scrap paper
Finding your Narrow Back Adjustment Measurement
To attain the measurement for a Narrow Back Adjustment, make a toile and put it on. Have another person pin the excess fabric at each of your shoulder blades equally, allowing for some/intended ease. Make sure that your arms can move freely and the fabric does not pull when reaching forward. Measure the amounts you removed by pinching, the average between both will be the amount you need to take that out of the pattern piece.
The easiest way to do this technique when you’re alone is to pinch out and pin a small amount at the position of each shoulder blade before putting the toile on. Wear the toile, check for fit and movement. You can then take off the toile, adjust the amount pinned, and put it back on until you’re happy with the fit and take the end measurement then.
Narrow Back Adjustment
1. Mark three lines on Back pattern piece as shown in the Broad Back Adjustment.
Cut the pattern along the lower horizontal line, meeting the vertical line. Slice up the vertical line until almost to the top, leaving a small amount of paper to work as a hinge. Starting at the vertical slash, cut along the upper horizontal line towards the armscye, again leaving a small amount of paper to work as a hinge.
2. Put a piece of paper behind your pattern piece, and tape the larger portion of your Back pattern piece down. Mark your pattern adjustment measurement at a point parallel to the vertical slash line, aligned with the upper horizontal line.
Pivoting from the shoulder hinge, swing the centre armscye slash across to meet your vertical mark. Tape the top adjustment piece to the paper underneath.
3. Hinge the pattern out from the armscye cut, back to line up with the lower horizontal slash line, as close as possible to the side seam. This helps to reclaim the waist measurement at that seam.
4. True up your pattern lines, and your Narrow Back Adjustment is complete!
You will likely not have altered the raglan/saddle shoulder seam length very much with the Broad/Narrow Back Adjustments for the Grove. But I would advise double checking the the armscye measurements to see if you need to add any or subtract length from your raglan sleeves. If you do, use the same technique that the Shoulder Width Adjustment for a Raglan Sleeve - Grove tutorial explains from step 7. Add or subtract any difference in measurement you encounter from the adjusted armscyes.
Your pattern pieces are now ready to use!
Remember, we always recommend sewing a muslin to test out your pattern adjustment before cutting into your fancy fabric.
Read more about common pattern adjustments here: