Open Laboratory

Precision tools for
crafters & makers

Free scientific calculators for soap making, woodworking, packaging design, brewing, and more. Real formulas, not guesswork.

Why precision matters in crafting

A wrong number in a soap recipe leaves free lye against skin. A miscalculated miter angle in a segmented bowl means a gap you cannot glue closed. A bend allowance off by half a millimeter turns a stainless steel bracket into scrap. The math behind handmade work is not decorative — it decides whether the piece is safe, whether it fits, whether the batch is worth keeping.

Craft Calc Lab is a set of 25 focused calculators built around the numbers real makers actually need. Every tool is single-purpose, runs locally in your browser, and shows the formulas it uses. Nothing is uploaded, nothing is stored, no account is required.

How we verify every formula

The internet is full of craft calculators that quietly disagree with each other. We take the opposite approach: every equation used here is traced back to a specific source and cited inside the tool page. Wood shrinkage coefficients come from the USDA Forest Products Laboratory. Saponification values are cross-referenced across three major supplier databases. Brewing ABV uses both the standard 131.25 factor and the corrected alternate formula for high-gravity worts. Bend allowance uses K-factor bounds published by sheet-metal fabrication references, not rounded shop-floor estimates.

When two published sources disagree, the tool documents the disagreement and lets you pick. When a formula only works within a range, the tool warns you outside it. We would rather show a range than a false precision.

Four labs, one workshop

The tools are grouped into four labs. The Recipe & Curing Lab covers chemistry-heavy work: soap saponification, resin ratios, emulsifier HLB, candle wax loads. The Geometry & Template Lab handles layout math: box die-cuts, calligraphy grids, book spine widths, mat board margins. The Fermentation & Food Lab covers what microbes and heat do to your ingredients: brewing gravity, sourdough hydration, meat curing salt safety. The Materials & Physics Lab predicts how physical materials move: wood shrinkage, clay firing, wax-to-metal casting, sheet bending, segmented ring turning.

Pick a lab below to see the full tool list, or jump straight into any calculator. Each page includes the formulas, safety notes, and a set of FAQs answering the questions makers usually ask after their first failed batch.