Pattern Alterations for Fit
(Customizing Sewing Patterns for Your Unique Body)
@EvelynWood
@EvelynWood
Step-by-Step Instructions:
Commercial sewing patterns are drafted for a “standard” body shape that rarely fits anyone perfectly straight out of the envelope. Learning basic flat pattern alterations allows you to tailor the blueprint to your exact curves and proportions before you even cut your fabric.
Materials Needed:
- Pattern tracing paper (medical exam paper works great)
- Clear acrylic ruler and a French curve
- Pencils, erasers, and clear tape
- Paper scissors
- Flexible tape measure
Tips for Success:
- Never cut your original tissue pattern! Always trace your size onto new paper so you can preserve the original.
- Make your alterations without seam allowances included, or draw the seam allowances in so you know exactly where the garment will sit on your body.
- Always test your altered pattern by sewing a muslin (toile) before cutting into your fashion fabric.
1. Take Accurate Measurements
- Take your high bust, full bust, waist, and hip measurements. Compare them to the pattern’s size chart. Pay close attention to the “Finished Garment Measurements” to understand how much ease (extra wiggle room) the designer included.
2. Grade Between Sizes
- If your bust matches a size 10 but your hips match a size 14, don’t just cut a straight size 14! On your traced pattern, mark the size 10 line at the bust and the size 14 line at the hip. Use a French curve to draw a smooth, gradually sloping line connecting the two.
3. Adjust the Length
- Look for the “lengthen or shorten here” lines printed on the pattern. To lengthen, cut along this line, spread the pieces apart by your desired amount, and tape them to scrap paper. To shorten, draw a new line above the cut line by your desired amount, and fold the pattern so the lines meet.
4. Address Bust and Shoulder Adjustments
- Patterns are typically drafted for a B or C sewing cup size. If you differ from this, you will need to learn how to do a Full Bust Adjustment (FBA) or Small Bust Adjustment (SBA) using the slash-and-spread method. Similarly, check if you need a broad or narrow shoulder adjustment.
5. True Your Seams
- Whenever you slash, spread, or fold a pattern, the outer cutting lines will become jagged. “Truing” means using your ruler or curved edge to draw a new, smooth, continuous line connecting the edges. Ensure that adjoining seams (like a front side seam and a back side seam) still match perfectly in length.
Top FAQs for Pattern Alterations:
Should I alter the pattern before or after making a muslin? +
Do your basic flat pattern alterations first—like grading between sizes, lengthening/shortening, and known full bust adjustments. Then, sew your muslin based on that altered pattern. The muslin will reveal the finer, 3D fitting tweaks you need to make (like adjusting a dart angle or a sloping shoulder).
What does “truing a seam” mean? +
Truing a seam means correcting jagged edges caused by altering a pattern. For instance, if you fold a pattern to shorten it, the side seam might look like a staircase step. Truing is taking a ruler and drawing a new, smooth line so the fabric can be cut cleanly, and verifying that the adjoining pattern piece matches that new length.
Why shouldn’t I just add width to the side seams for a larger bust? +
Adding width only to the side seams distorts the armhole and the neckline. More importantly, it doesn’t add the necessary vertical length or 3D volume needed at the apex (the fullest part) of the bust. A proper Full Bust Adjustment (FBA) adds room exactly where it is needed without ruining the rest of the garment’s proportions.
