Sømometer, Saummass, Zoommaatje, Seam gauge, Pfiffkus. It has many different names in Europe, but the purpose is the same – making the dreary process of adding seam allowances to patterns a little easier.
It’s a simple but pretty ingenious tool. As you can see in the picture, every corner has fixed width, ranging from 1 cm (~ 6/8 inches) to 6 cm (~ 2- 3/8 inches).
What you do is align the seam gauge along the stitch line and mark the seam allowance with little dots. Obviously the more dots the more precise the line will be. But you can get away with just a few dots as well.
For curved seam I often use my flexible ruler that I align with the dots.
1 cm (6/8 inches) added to a pattern for a jersey top. This method is both quick and accurate.
The seam gauge is made in either plastic, cardboard or metal and comes in several different versions. The metal gauge shown in the pictures is my favorite as it’s also a great tool when folding and pressing hems. Just fold the fabric over the chosen width and press.
Another version of the seam gauge.