A small workshop in public.

What this is

Komon Lab is a single tool with a small library of long-form guides around it. The tool turns seven body measurements into a printable kimono pattern. The guides explain the assumptions inside the tool — how to measure, what the fabric widths mean, which sewing tools are actually worth owning, what changes between yukata and kimono construction — so you can disagree with the tool when it is wrong.

The site is built as a static set of pages: no server, no database, no account system. Your measurements are entered in the browser, run through the generator in the browser, and turned into a PDF in the browser. Nothing about your body leaves your device. If you close the tab without saving the PDF, every byte of what you typed is gone.

Why it exists

The English-language kimono sewing internet has a strange shape. There are excellent Japanese-language books, a few translated patterns, and a long tail of forum threads. What there is not much of is a tool that takes your measurements and gives back a pattern. Almost every English-language option is graded from a single fictional standard body, with two or three alternative sizes on a good day.

That mismatch makes kimono sewing feel inaccessible to people whose proportions do not fit the chart, or who can only source 110 cm fabric. Komon Lab is a small attempt to fix that — by treating the proportional rules of traditional wasai as a generator, not a frozen size grid. The methodology page describes how those rules are translated into measurements, and our methodology page gives the maths in detail.

Who builds it

One person, working in the evenings. The project author is a sewer who got frustrated with the available options and started writing code — not a heritage tailor, not a credentialed sewing instructor, not a credentialed Japanese-clothing historian. That framing is important because it sets the scope: this is a serious technical project, but it is not a substitute for the deep knowledge held by professional wasaishi in Japan. Where we have simplified or made trade-offs, we say so.

For now, the project is intentionally anonymous. The work stands or falls on whether the patterns fit, the guides explain things correctly, and the maintainer responds well to feedback. If contributors join in future, they will be listed here by name with their consent. The intent is editorial transparency without celebrity.

Editorial process

Every guide on this site goes through the same three-pass review before it is published:

The first pass is structural. Does the guide answer a real question an English-speaking sewer would actually ask? Is the question one that a beginner can find by searching, and an intermediate can return to without feeling talked down to? If the structure is wrong, the guide goes back to outline.

The second pass is factual. Each claim about wasai tradition, fabric behaviour, or measurement convention is cross-checked against at least two sources from the established literature — typically including some combination of Liza Crihfield Dalby's Kimono: Fashioning Culture, John Marshall's books on Japanese sewing, the writings of Yoshie Hatae and other published wasaishi, and contemporary Japanese sewing curricula. Where sources disagree, we describe the disagreement rather than pick a side silently. Where we are simplifying for tool tractability, we say so in the text.

The third pass is language. The site is written in English for English-speaking sewers, but it is written about a Japanese craft. Where a Japanese term is the precise one — mitake, yuki, okumi, eri, tan-mono — we use it and define it on first appearance. Where an English term will do without distortion, we use English. The aim is that a reader who finishes a guide can read a Japanese sewing book and recognise the vocabulary, not that they have to learn Japanese in order to use the tool.

A small note on AI assistance. Drafts may be sketched with the help of language models, but every published guide is edited end-to-end by a human, and every claim of fact is verified manually against a source. The voice and the responsibility for accuracy are human.

How the tool was built

The generator started as a spreadsheet. The first version was a series of cells that took body measurements and computed the eight main panel dimensions of a women's adult kimono — body width, body length, sleeve depth, sleeve length, collar overlap, okumi width, back-seam offset, hem allowance. Once the cells produced reasonable numbers on three test bodies of very different proportions, the formulas were ported to JavaScript and wrapped in the in-browser tool you can use today.

The next layer was the cut chart. A kimono is traditionally cut from a single bolt of tan-mono 35–38 cm wide, but most Western fabric is 110, 140, or 150 cm. The cut chart rotates and splits the panel layout for the actual width on hand and gives a yardage figure. The logic for this is described in the fabric widths guide and again, in computational form, in the methodology.

The PDF is built with pdf-lib, a browser-side PDF library. Pieces are laid out as cuttable rectangles with seam allowances and labels, sized to A4 or US Letter at one-to-one scale and tiled across as many pages as needed. Everything is rendered on your device. Nothing is uploaded.

History of the project

The project began as a personal frustration: a finished kimono that hung off one shoulder because the only available pattern was sized for proportions that were not the maker's. The first version of the spreadsheet was a one-evening attempt to recompute the panel dimensions for a longer back. It worked, surprisingly well, and the question changed from "can I fix this one kimono" to "could other sewers use the same logic."

The site went public in 2026, as a static Astro project on Cloudflare Pages, with the tool, eighteen guides, and a small set of supporting pages. The compare and methodology pages were added in the same year. Subsequent versions are likely to add a juban (under-kimono) generator, a haori (jacket) generator, and a children's age-fold calculator. The current scope deliberately excludes the more historically loaded garments — furisode, uchikake, ceremonial layers — because the proportional logic is the same but the cultural responsibility for getting them right is much higher, and the project is not yet old enough to claim that responsibility.

A version history is maintained in the methodology page so readers can see how the generator's formulas have changed over time, and reproduce older outputs if they want to.

Open source and methodology

The maths in the tool is documented in the open. The methodology page describes the proportional rules used to derive each panel dimension from body measurements, names the published sources behind each rule, and lists the known limits where the rules break down.

The source code for the website is, as of writing, kept private but auditable: anyone who finds a numerical disagreement with a published source can email and ask for the exact formula that produced a given output. The plan is to make the code public on a permissive license once the formulas have been reviewed by a small number of wasai-experienced sewers, so that the public version cannot be misinterpreted as authoritative before it has earned that.

The position is, in short, "open methodology now, open source soon." If you want the formula for a particular dimension and you cannot find it on the methodology page, write and ask.

How it stays free

The site is statically built and hosted on Cloudflare Pages, which is free at this scale. The pattern PDFs are generated in your browser, which means we do not pay for compute when you make one. Analytics is Cloudflare's own privacy-friendly counter, which is cookieless and does not identify visitors.

The only revenue stream, and a small one, is Amazon affiliate links inside the guides — labelled, for items the author would already recommend. These are clearly disclosed at the top of every guide and detailed on the affiliate disclosure page. There is no paywall, no email list, no premium tier, no sponsored content, and no plan to add any of those things.

If hosting costs ever exceed what affiliate links cover, the next step would be a small set of unobtrusive editorial ads on the guides — again labelled, again for things the project would recommend without payment. The plan is to never put anything between a reader and a working PDF.

How to help

Sew a kimono from the tool and tell us what failed. Photos of the fit issue help more than words. Tell us where the cut chart confused you, where a guide assumed knowledge you did not have, where a Japanese term went undefined. If you can read Japanese sewing books and spot somewhere we have simplified the maths in a way that breaks tradition, write — that kind of correction is exactly what the project depends on.

If you teach kimono sewing — in a college course, a community workshop, a private studio — and the guides would help your students, please use them freely. The license is friendly to non-commercial educational use, and the maintainer is happy to extend explicit permission for a specific course if you ask.

Press and mentions

The project is new and we have not actively sought press. As of this writing, no mainstream publication has reviewed Komon Lab. If you are a writer, blogger, or YouTuber considering covering the project, you are welcome to use any of the images on the site, and the maintainer will respond to interview requests at the contact channel below.

Mentions of the project in other places — sewing blogs, finished-make posts, forum threads — are also welcome. A simple link to komonlab-site.pages.dev is enough, no permission needed. If you would like a quote about the project for a piece you are writing, send an email and one will be written in your timeframe.

Contact

A public contact channel is being decided. In the meantime, please hold onto your feedback — it will be wanted as soon as one is open. If you have urgent feedback (a factual error in a guide, an obvious bug in the tool), please come back to this page in a few days and the channel should be live.

If you have read this far and want to try the tool, the pattern generator is one click away. If you would rather start by reading, the guides index lists every long-form piece on the site, and our methodology page covers the underlying maths in detail.