Methodology & Editorial Process
How we source formulas, verify accuracy, and keep every calculator honest about what it can and cannot do.
Who We Are
Craft Calc Lab is maintained by a small team of practicing crafters — soap makers, woodworkers, brewers, and ceramicists. We are not a publisher, a marketing agency, or an AI product. Every calculator on this site was built by someone who needed it for their own work and could not find a version that showed its math.
Because our team is small and cross-disciplinary, each calculator is reviewed by the team member with the most direct experience of the craft involved. Soap chemistry gets reviewed by a soaper, wood shrinkage by a woodworker, food-safety math by someone who has had to hit a nitrite target on a real cure.
How We Source Formulas
Every formula in every calculator is traced back to a published reference. We prefer, in this order:
- Peer-reviewed literature or government technical publications (e.g., the USDA Forest Products Laboratory Wood Handbook for wood shrinkage coefficients).
- Industry-standard reference books or manuals (e.g., Modern Soapmaking for saponification tables, the SCA Coffee Brewing Handbook for extraction targets).
- Multiple reputable supplier or trade databases cross-referenced against each other, where no single authoritative source exists (e.g., candle wax fragrance-load limits, which vary by wax manufacturer).
When two sources disagree, the tool documents the disagreement and exposes the choice as an input. We would rather show a range than invent a false precision.
How We Review a Tool
Before a calculator ships:
- The formula is written down with its source citation.
- The formula is cross-checked against a second reference. If the two disagree, we investigate before publishing.
- A worked example is run through the calculator and compared against the same example computed by hand. They must agree.
- Known limitations are enumerated on the tool page under "Limitations & What This Tool Cannot Do." If we cannot list at least three honest limits, the tool is probably too shallow to publish yet.
- The tool is dated with the review date. When a formula gets updated, the review date rolls forward.
How Errors Get Corrected
If you spot a wrong formula, a citation that does not check out, or a calculator that returns an implausible result, please let us know. Include the tool name, the inputs you used, the result you got, and the result you expected. We prioritize formula corrections over feature requests and typically ship a fix within 2-3 business days.
What We Will Not Do
- Fake reviews or testimonials. No calculator page carries invented user quotes or fake star ratings. If we cite user feedback, it is real feedback we received via the contact form and reused with permission.
- Undisclosed affiliate links. If a tool ever links to a product or supplier and we earn a commission, it will be marked clearly. Right now no tool contains any affiliate link.
- Invented sources.Every entry in a tool page's "References" section must correspond to a real, findable publication. Where a formula is common practice with no single authoritative source, we cite it that way honestly.
- Over-claiming precision.If a calculator's output depends on inputs we cannot measure precisely (species-level wood variation, batch-to-batch oil variation, ambient humidity), the tool says so.
Formula Update Policy
When a source we cite publishes a revised edition, we update the tool on our next review pass and roll the "Last reviewed" date forward. When a broader craft community consensus shifts (for example, if the SCA revises its Gold Cup extraction range), we update within one month and note the change on the tool page.
Last updated: July 29, 2026.