PRODUCT
ShirtMath matches a garment your shopper already owns against your catalog and returns the best-fitting size and product matches — by measurement, not by size label.
Last verified: 25 August 2026
WHAT A RESPONSE CARRIES
Illustrative: the shape of a response, not a customer's traffic. ShirtMath is pre-launch and has no customers, so there are no usage figures on this page.
Engineered for accuracy, built for retail
ShirtMath is pre-launch and has no customers, so there is no logo wall here and no service-level figure to quote. What follows is what the service does and does not do this week, named the way the code names it.
A CSV product feed, a JSON product feed and a custom retailer API are implemented. Shopify OAuth, WooCommerce and BigCommerce are listed as coming soon and are not built — asking for one returns an error that says so rather than a half-working import.
A product with no published measurements returns INSUFFICIENT_DATA. When no fit authority can be reached at all, the API returns FIT_AUTHORITY_UNAVAILABLE. A confident wrong guess produces exactly the return you bought this to prevent.
Fit responses run on contract b2b-fit/1.0.0, status PHASE4_ACTIVE_STAGING. Every response carries an authority field, so your integration can branch on how much an answer is worth instead of assuming they are all equal.
A sandbox workspace receives a clearly-labelled synthetic demonstration carrying authority SANDBOX and customer authority false. It is never dressed up as a fit claim, in the response or on the page.
Every touchpoint
Two surfaces ship together: a widget that mounts into your product page, and a portal where you can see what your catalog can actually support.
A control appears beside the size selector: not sure of your size? Match it to a shirt you own. The widget renders the answer inline — in your styling, on your own domain.
The portal counts, in your catalog, how many products carry a chart worth comparing — and separates a garment-measurement chart from a body-measurement chart instead of treating them as the same thing.
The connection view names the provider, the verified domain, the last sync and the last error, so a broken feed is visible rather than silent. Feeds are fetched https-only, redirects refused, with size and time limits.
An event log rather than a marketing chart: what your integration did, what happened, and the code that came back. There are no numbers in it yet, because there is no customer traffic yet.
What the platform returns
The response tells you what kind of answer it is before it tells you the answer.
The single best-fitting size for that shopper in that product, with the alternatives it considered alongside it.
Every response states how much its evidence is worth. VERIFIED_FIT means garment-to-garment measurements on both sides; QUALIFIED_SIZE_GUIDANCE states its own limitation.
Candidates from your own catalog and nobody else's. A tenant is its own catalog scope, and there is no fallback to another retailer's products or to the consumer catalog.
Which measurements matched and which did not, so the shopper is told why a size fits rather than asked to trust a number. Where the evidence is missing, that is what it says.
How it works walks the four steps end to end. The developer documentation carries the endpoints, the key lifecycle and all six statuses. Pricing is $320 a month or $3,400 a year, and the FAQ answers the sixteen questions retailers ask most.
More for brands
Publishable keys, signed widget sessions, verified domains, the match endpoint, and its honest no-answer status.
The three built connectors, field maps, paging, and what a partial or failed import does.
What happens after the size-chart modal, and how a garment chart is kept distinct from a body chart.
Where a fit return actually comes from, and which part of it a measurement comparison can address.
Process versus prevention: what a returns workflow does after the fact, and what has to happen before checkout.
The project behind the engine, and the data rules that govern the consumer site and this one alike.
See the fit engine your customers would use. It runs on this site, on the same measurement rules — including the part where it declines to answer.
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