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FibreCalcs

About FibreCalcs

FibreCalcs is the textile-crafts entry in a portfolio of niche calculator sites I build. Every calculator here is grounded in a published source, coded against an automated test, and checked against independent references before it ships. I’m a system architect, not a maker — the value I bring is methodology, not personal craft experience.

Who’s behind this

My name is Dan Dadovic. I’m the Commercial Director at Ezoic Inc. and a PhD candidate in Information Sciences at the Faculty of Organization and Informatics (FOI), University of Zagreb (EQF 8 — in progress, not held). I hold a Master’s in Informatics and a Master’s in Economics from the same institution (both EQF 7), and a Bachelor’s in Informatics (EQF 6). My academic background is quantitative and computational, which is the lens I bring to building reference tools.

To be direct about what I am and what I am not: I have no hands-on textile-crafts experience. I do not sew, quilt, knit, crochet, or make curtains. I have not stood at a cutting counter wondering how much to buy. The calculators on this site are not built from personal practice — they are built from published textile sources and verified against automated tests, with every result-driving value traced to references you can check. That is the model I think actually deserves your trust: a transparent stack of references and tests, not a borrowed maker persona.

How the calculators are built

Every calculator on FibreCalcs follows the same build process. The formula comes first. Before any code is written, I track down at least one published reference — a textile handbook, an industry standards body, or documented professional practice. For quilt backing the references are Robert Kaufman’s published fabric width specs and Missouri Star’s piecing guidance. For yarn yardage it is the Craft Yarn Council’s Standard Yarn Weight System. For curtain fabric it is workroom practices documented by professional curtain makers, including Cindy Taylor’s detailed guides at sew-helpful.com. For fabric weight the reference is the ASTM textile standards.

Then the formula gets coded, and every code change runs through 188 automated tests. Worked examples on every calculator page use inputs that are actually run through the function — the intermediate values and final result shown in the prose are what the code produces. If the calculator changes, the examples fail and have to be updated. The paperwork has to match the cloth.

Every result-driving value is checked against published external sources before it ships — at least three independent, authoritative references, or the originating manufacturer’s or standards body’s own publication, each opened live and recorded with a dated provenance entry. Where a figure couldn’t be pinned to a source that meets that bar, the page says so plainly rather than borrowing authority it hasn’t earned. No external reviewer has signed off any page yet; when one does, the credit will appear with the committed review record behind it.

One example of the difference the source-driven approach makes: the curtain fabric calculator has a straightening allowance toggle. Professional curtain makers trim 5cm off each end of plain (unpatterned) fabric to square the grain before cutting drops — standard workroom practice for cloth that came off the bolt slightly off-grain. Most online calculators skip it. This one includes it because Cindy Taylor documents the practice and ignoring it means a finished curtain hangs crooked. The same source-driven logic shapes the quilt backing calculator, which compares horizontal and vertical seaming and recommends whichever direction wastes less fabric, and the yarn yardage calculator, which accounts for stitch-pattern yardage differences rather than using a single average.

You can read more about sourcing and verification on the editorial policy page. A worked example of the curtain maths in full is in the curtain fabric guide.

The other calculator sites I build

FibreCalcs isn’t my first calculator site. I build tools for specific trades and crafts, each one purpose-built for its audience rather than retro-fitted from a generic template. The pattern is the same across all of them: research the niche, verify formulas against industry sources, write automated tests, draw presets from how practitioners actually work — and, where I lack the domain experience myself, lean on published references rather than borrowing a persona.

The methodology carries across every site, and the textile calculations here are held to the same standard.

What this site is not

FibreCalcs is not a replacement for measuring your own project. No calculator can account for your specific fabric’s selvage width, your tension running tight on a cold morning, or the fact that your curtain pole isn’t perfectly level. The results here are planning aids — they get you to the fabric shop with a sensible number, not a guarantee.

Always buy extra. Ten to fifteen percent on top is a reasonable rule of thumb for fabric, an extra skein from the same dye lot is the rule for yarn, and measure twice before cutting. The calculator’s job is to save you from a second trip to the shop, not to remove the need to think.

Get in touch

The feedback form at the bottom of every page comes to me. Useful feedback includes: a formula that produced a result you think is wrong (tell me the inputs and what you got), a calculator you’d like to see added, a preset that would cover a common scenario I’ve missed, or a source you think I should be citing that I’m not.

Spot something I’ve got wrong and I genuinely want to know. Every report gets read. Confirmed errors get fixed, the affected pages flagged for review, and the test suite updated so the same mistake can’t happen twice.

FibreCalcs is free, has no ads, and requires no login. If it saves you a trip to the fabric shop, it’s done its job.