Make the assumptions visible.
Swatch & Skein is a small independent crochet planning tool. It estimates yarn for a rectangular blanket by scaling the weight of your measured sample to the area of the intended fabric.
What it is designed to do
Show the formula, accept your real measurements, explain the allowance, and optionally translate grams into label-based lengths and whole skeins. A downloadable worksheet keeps those assumptions alongside the result so you can revisit your plan later.
What it does not claim
This site does not have a validated database of typical yarn quantities for every stitch or project. It does not claim professional certification, testing by crochet experts, or guaranteed quantities. It is not affiliated with the Craft Yarn Council, any yarn brand or other calculator.
The mathematical formula and conversions have automated numerical tests. That checks the arithmetic; it does not establish how closely an estimate will match a finished blanket. That depends on your sample and how the final fabric is made.
Keep it practical
The first version deliberately focuses on repeating rectangular fabric and needs no account, upload or subscription. It is free to use. There are currently no advertisements, affiliate purchase links or payment features.
Begin with the measurement guide, especially the rule that the weighed sample and measured area must match. Then compare the result with your pattern and real progress.