Seam Allowance Basics

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What Is A Seam Allowance?

A seam allowance is the simply the area between the edge of your fabric and the line of stitching being used to join two or more pieces of material together. The amount of seam allowances can range from 1/4 inch wide to as much as several inches. Commercial patterns for home sewers normally have seam allowances ranging from 1/4 inch to 5/8 inch. This measured distance is the width between the ragged edge and where the seam is to be stitched. Sometimes the type of pattern, design, or fabric requirements determines which size seam allowance will be used.

Is There A Standard Seam Allowance?

That depends a what kind of project that you are sewing. A 5/8″ (1.5cm) seam allowance is generally considered a standard. As this provides enough extra between the seam line and the cut edge of the fabric to ensure that the layers are all stitched when joining. It is also important for materials that unravel easily. A 5/8″ (1.5cm) seam allowance is also easier to work with when pressing a seam open or topstitching it for a finishing touch. Finally, it also provides a small amount of “letting out” space if a garment needs to be just a little bit looser.

For curved areas, such as neck lines or arm holes, the seam allowance maybe only 1/4″. But in areas that need extra fabric for final fitting for the wearer seam allowances can be 1″ or more.

A Few Seam Allowance Tips

  • Read through a pattern before starting a project, make note of the seam allowances
  • Garment patterns with multiple sizes – the printed lines on the tissue paper are the cutting lines with the seam allowances already added
  • If a seam allowance is adjusted in one place, it will also need to be adjusted in corresponding areas
  • Check the seam lines on the throat plate on your sewing machine for accuracy, sew on a piece of paper without thread in the machine and measure the distance from the edge to the stitching line and the edge – make adjustments as necessary