Different seams do different jobs! In our pattern instructions, these terms help you identify where to fine-tune your fit and where to follow the specified seam allowance.

Adjustable seams: for fine-tuning fit Adjustable seams are seams you may need to change to make your garment fit comfortably. Examples include: Seams that shape the bust, waist, or hips Inseams and outseams on pants These are places where you can take a garment in or let it out, depending on the fabric available. “Adjustable” means we've built in the ability refine the fit with a bit more seam allowance than usual, not that every project will need an adjustment.

Non-adjustable seams: for assembling details Non-adjustable seams connect or construct parts of the garment that typically don’t need fitting adjustments. Examples include: Pocket construction and attachment Placket construction Collar attachment For these seams, follow the seam allowance listed in your instructions. Changing it can affect a detail’s size, shape, or how it lines up with adjoining pieces.

Why the difference matters

Your seam allowance is the distance between the stitching line and the cut edge of your fabric.

Changing that distance at an adjustable seam can change the garment’s fit, but changing it at a non-adjustable seam can affect how the garment goes together.

Before finishing: Check the fit while adjustable seams are still easy to access and alter. Larger fit changes may require adjusting the pattern before cutting.

When in doubt, make a mock up before sewing in your final fabric!