We regularly get questions from our North American customers about why our seam allowances are not wider. I'm sorry but we are sticking with the 1 cm (3/8") seam allowances and below are some reasons why!
European patterns tend to recommend / include just 1 cm (3/8") seam allowance. We like this amount because it doesn't waste fabric and ends up less bulky along the seams. 1/2" seam allowances are common with American sewing pattern brands. For a beginner it might be easier to work with a wider seam allowance, but as your skills grow, a narrower seam allowance is always going to result in a more professional looking garment. You can always trim seam allowances after sewing, but that adds another step to your project.
In garment manufacturing seam allowances above 1 cm are very rare, in fact they are often even less, the main reason obviously being the savings on materials, but it's also proof that it's possible to learn to work with a narrower seam allowance, and that sewing machines are designed for it.
If you're working with a very delicate fabric that frays easily, it might be a good idea to add more seam allowance to keep the seams from stretching when sewing. Another reason might be that you're unsure of the fit and want to be able to give more width to the garment after the initial fitting. In that case feel free to add your preferred seam allowance following our tutorial!
