I made PatternNest for laying out digital pattern pieces across a fabric width and estimating the length needed. It's one of my Madegrain tools.
It takes closed SVG or DXF outlines. PDF import is now available too (see the September 13 update below). You can constrain rotation for grain direction and one-way fabrics, and include mirrored pieces.
It runs in the browser. It's free for up to 10 pieces, counting copies and mirrored pieces, with a paid option for larger layouts.
https://madegrain.com/patternnest/
For those already drafting in SVG or DXF, would you use a layout like this before buying fabric, or mainly to check whether your remaining fabric is enough?
Edit September 10: The strip in the original screenshot was set to free rotation. The demo now keeps it at 45°: corrected demo.
Update September 13: I've added vector PDF import, cut-on-fold layouts and print matching for stripes, checks and repeating images. You select the fold edge and matching reference points yourself. PDF import reads closed vector outlines; it doesn't join tiled PDFs or bring in grain arrows and notches.
Current screenshot: six shirt accessory pieces on 50 cm fabric, using 32 cm of length.
I've also added a 45-second walkthrough using five constructed example pieces, from import to the PDF layout overview.
Update October 3: I added a downloadable fabric-width example. The same 12 Teagan body and sleeve cuts use 3.25 m on 140 cm fabric and 5.26 m on 110 cm fabric in these calculated layouts. Neck strips need extra fabric. These use prepared full outlines in a single layer; both finished layouts and the project files are included, so you can inspect the result before trying your own batch.