Your questions, answered.

HeyFit is installed from your store’s Shopify admin. Shopify asks you to allow read access to your catalog, then HeyFit opens right inside the Shopify admin: no extra account needed.

On the home page, the “Get started with HeyFit” list guides you: create a size chart, assign it, turn on the button, then, if you wish, connect HeyReturn. Steps check themselves off as you go.

Garments chosen by body measurements: tops (chest, waist), bottoms (hips, waist) and other pieces (chest, waist, hips). The customer answers the girth measurements your chart contains, and the inseam for a bottom or another piece, which checks the length without changing the size.

HeyFit doesn’t guide shoe sizes or children’s sizes given by age: for those products, don’t assign a chart, or assign an “other” chart that works as a plain size table.

Read access to your catalog only (Shopify read_products scope), to check that your size charts match your products’ sizes. HeyFit never changes your products, orders or customers.

Yes, on app.heyfit.app, with your Heylio suite account (the same as for HeyReturn and HeyTracker). You’ll find all your account’s stores there, and switch between them with the selector at the top of the menu.

In the Shopify admin: Online Store → Themes → Customize, pick the Product template, then Add block → Apps → “Find my size (HeyFit)”. Place it wherever you like, for instance below the size selector, and save.

Faster: the “Add app block (2.0 themes)” button in the “Get started with HeyFit” list opens the theme editor with the block ready to place; “Turn on automatic embed” does the same for the automatic embed described below.

Use the automatic embed: in the theme editor, open “App embeds” and turn on “Find my size — automatic embed (HeyFit)”. The button places itself below the add-to-cart button, on every theme, older ones included (Debut…).

If you also add the regular block to the product page, the automatic embed steps aside: the button never shows twice.

The button only shows when everything is in place:

• a size chart applies to the product (see “How do I assign a size chart to my products?” below);
• at least one size of that chart matches the product’s sizes (an “S, M, L” chart can’t serve a product sized “38, 40, 42”);
• the block or the automatic embed is turned on in the published theme;
• on the Free plan, the size chart is your published one (the first you created): the others are kept but only show with HeyFit.

In the theme editor, a notice tells you when no size chart applies to the product shown, or when its sizes don’t match the product’s. Otherwise, the product page works normally, just without the button.

Two tabs: “My size” and “Size chart”. In “My size”, the customer enters at least one body measurement (or, if they don’t know them, their height, weight and age: see the next question) and says whether they like to wear their clothes snug, regular or loose; they get the recommended size, with a confidence score and a measurement-by-measurement breakdown, and a “Select size …” button that picks it on the product page.

• “How to measure”: a figure shows where to place the tape measure for each measurement (chest, waist, hips, inseam), with a tip;
• centimeters or inches: the customer picks their unit, whatever your chart’s unit (the chart, the inputs and the advice follow); their choice is remembered on their device. Until they choose, the guide opens in inches for a customer in the United States, Liberia or Myanmar, in centimeters elsewhere, and in your chart’s unit if their country is unknown or in the United Kingdom (where both units are in use); in inches, height is entered in feet and inches and weight in pounds;
• their measurements can be kept in their browser for your other products: see “Does HeyFit store my customers’ measurements?”.

Yes: in “My size”, they choose “I don’t know them” and enter their height, weight, age and body type (female, male or not specified). The guide estimates their measurements in their browser, from public anthropometric reference data, then recommends a size as usual.

The advice is shown as estimated, less reliable than with real measurements; if the customer falls between two sizes, the guide says so and recommends the more likely one. Their height, weight and age are never sent to our servers, which only receive the estimated measurements. The Statistics screen separates advice based on measurements from estimated advice.

The guide says in words, never as a percentage, how sure the advice is:

• “reliable advice”: all the customer’s measurements fall within the recommended size;
• “check this advice”: not all their measurements fit this size; the details by measurement show it;
• “take this advice with care”: their measurements fall outside your chart (below the smallest size or above the largest) and the guide suggests the closest one, or the recommended size replaces one your product doesn’t sell;
• “estimated”: the customer entered their height, weight and age instead of their measurements (see the previous question).

“We can’t recommend a size” shows when none of the measurements entered is used by your chart (for instance only hips, for a top chart without hips): the customer is then invited to check the size chart. The more complete your chart, the rarer this is. Measurements more than 10% outside your chart show “This product has no size for these measurements” (see the next question).

The guide asks the customer for every girth measurement in your chart (chest, waist, hips), and the inseam for a bottom. The recommended size is the one that fits all their measurements:

• if their measurements point to different sizes (chest in M, waist in L), the guide recommends the larger one, so nothing feels tight, and says so;
• a measurement right on a limit shared by two sizes (M 90–96, L 96–102) goes to the larger one, unless another measurement points to the smaller; within 2 mm, so the advice is the same in centimeters and inches;
• the inseam checks the length (“on the short side”, “on the long side”) without changing the size;
• “Snug” or “Loose” shifts by one size only if all measurements are in the lower (or upper) half of the size;
• never a size your product doesn’t sell: if it’s missing, the guide offers the neighboring size and says so, or says it isn’t available;
• measurements more than 10% outside your chart get no size, and a value outside 50 to 200 cm for a girth (40 cm for the waist) or 25 to 110 cm for the inseam is refused when entered.

The advice is only called reliable when all the customer’s measurements are within the recommended size. The recommendation preview, on your size chart’s page, asks the same questions and gives the same advice as your store.

Yes, in the block settings: button text (empty: “Find my size”, translated to the store’s language), appearance (button or link), button and text colors (empty: your theme’s). If the contrast is too low, the text switches to black or white automatically.

Start from a template (top, bottom or other) and adjust the measurements to your fits: chest, waist, hips, inseam, each with a minimum and a maximum per size. Measurements are entered in centimeters or inches; switching units converts the values (rounded to the nearest half). The template is created in your store’s usual unit: inches if it sells in US dollars, Liberian dollars or kyats, centimeters otherwise.

You can also start from a blank chart, or reuse the table you already have: from a CSV file, or with AI, from an image, a web page or a product description (see below). HeyFit flags overlapping sizes, and checks that the chart’s sizes match your products’ sizes.

Yes: export it as CSV, then use “Import a size chart from a CSV”. The file contains:

• a size column (or taille), then the columns in any order;
• then a …_min / …_max pair for each measurement: chest, waist, hip, inseam — French headers are also accepted: poitrine_min, tour_de_taille_max, hanches_min, entrejambe_max…;
• a comma, semicolon or tab separator; with a semicolon or a tab (French Excel exports), a decimal comma is accepted (“82,5”);
• 40 sizes and 100 KB max.

Values are in the unit chosen for the import (centimeters or inches). A header can state it, for example “chest_min (in)” or “poitrine_min cm”: the unit is then taken from the file, and a file that mixes both is rejected. If the values look like the other unit (96, 102… in an inches chart), HeyFit tells you.

A preview shows the sizes read before anything is created. Nothing is created while a row has an error: each error gives its row.

Yes: “Create a size chart”, then “Import with AI”, from one of these sources:

• an image: a screenshot of your size table (PNG, JPEG, WebP or GIF);
• a public web page: the size guide on your site or the brand’s;
• the description of a product in your store that already contains the table.

The AI (Anthropic’s Claude, via OpenRouter) reads the table and suggests a size chart, with the points to check. Nothing is created on its own: you review every size and measurement, fix what needs fixing, then click “Create the size chart”. Only the content you chose is sent, once, and it isn’t kept: no customer data.

20 AI imports per store per day (the counter resets at midnight, Paris time); an import the AI service couldn’t process isn’t counted. Importing is reserved for owners and administrators; on the Free plan, you need a free slot for the chart.

Yes: the chart’s “History” panel keeps its last 50 changes (who, when, what). “Restore this version” brings back that version’s name, category, unit and sizes; assignments don’t change. The restore is itself added to the history: nothing is lost.

Duplicating creates a copy of the chart, named “… (copy)” (the name stays editable), with the same sizes and measurements but no assignments: a target only has one chart at a time. The copy has its own history.

Deleting is final: the chart, its assignments and its history are erased, and “Restore this version” is no longer possible. Its products immediately get the next chart that still applies to them (collection, product type, then default chart), or no button if there is none. To keep a record, duplicate it first.

From the size chart, assign it to products, a collection, a product type, or make it the store’s default chart. When several charts could apply, the most specific wins: product, then collection, then product type, then default chart.

The Products screen shows, for each product, the chart that applies and where it comes from, and helps you find products without a chart to assign them one in a single step.

If your store uses HeyReturn, from the same Heylio suite, it automatically sends HeyFit the items returned for a size reason (“Too small”, “Too large”). HeyFit counts them product by product, in the “What your returns say” screen.

• From 3 returns that say which way an item is off, a trend appears (“runs small”, “runs large”), to be confirmed.
• From 5, it becomes advice: on the product page, the size suggested to the customer moves by one size, and the size from the chart stays visible next to it, with the explanation.

Yes: in “What your returns say”, state yourself that a product runs small, runs large or is true to size. Your statement always takes precedence over what returns say, and applies right away.

Yes, on request: write to us at hello@heylio.io. We import your store’s history of size-related returns from HeyReturn (product, returned size and wanted size, with no data about your customers), and it applies as soon as HeyFit is installed: your products’ trends and advice take it into account right away.

The Statistics screen shows what the button does on your store, over the last 7, 30 or 90 days:

• displayed recommendations, day by day: each time a customer gets a size on a product page;
• recommended sizes, and the share of reliable advice (all the customer’s measurements within the recommended size);
• advice followed: after a recommendation, the share of customers who pick the recommended size (“Select size …” button, the product page’s size picker or add to cart);
• advice corrected by your returns or your statements, and size returns received from HeyReturn.

Estimated advice (height, weight and age) is counted separately from advice based on measurements. Everything is anonymous: HeyFit only counts numbers, with nothing that points to a customer. A day runs from midnight to midnight UTC. On the Free plan, no size is recommended: the screen stays empty.

The admin is available in six languages: French, English, Spanish, German, Italian and Dutch. By default (“Automatic”), it follows your browser’s language; if your browser uses none of these languages, your Shopify admin’s language, otherwise English.

You can choose it on the “My account” page (your account menu, at the bottom of the sidebar): Automatic, Français, English, Español, Deutsch, Italiano or Nederlands. Your choice is kept on your account and, if you have a Heylio account, applies across the Heylio suite (HeyReturn, HeyTracker…).

The button and the size guide come in six languages: English, French, Spanish, German, Italian and Dutch. They show in the store language the customer is browsing, and in English for other languages. A button text entered in the block settings replaces the default text, in every language.

Two plans:

• Free, with no subscription: 1 published size chart, and the size table on your product pages (the button then reads “Size chart”); no size recommendation, no “Select size” and no learning from HeyReturn returns;
• HeyFit, all included: unlimited size charts, size recommendations, “Select size” and learning from returns — €19 per month if Shopify bills your store in euros, $19 (US dollars) per month otherwise, plus applicable taxes, with a 14-day free trial.

The subscription is billed by Shopify, on your Shopify bill: HeyFit never sees your payment method. Prices exclude taxes: any applicable VAT or local tax is added by Shopify to your bill.

The trial applies once per store, and its end date is set as soon as it starts: it never pauses. If you switch back to the Free plan or uninstall HeyFit, then come back before that date, you only get the days left until it; after it, the subscription starts with no trial.

With the “Upgrade to HeyFit” button, in the banner at the top of the pages, in Settings or wherever a feature is reserved for HeyFit: Shopify shows you the plan, which you approve. Only an owner or an administrator can activate it.

Without an active subscription or running trial, your store is on the Free plan: only your first size chart stays published, as a size table. Your other size charts are never deleted: they are kept, not shown, and come back as soon as you upgrade to HeyFit.

In Settings, Subscription card, click “Switch to the Free plan” (owner or administrator): the subscription stops right away in Shopify, with no refund of the current period already paid. Your store moves to the Free plan: nothing is deleted, and your first size chart stays published as a size table. A running trial stops too, and keeps its end date (see “How much does HeyFit cost?”). There is no minimum term.

Uninstalling HeyFit from the Shopify admin also stops the subscription, with no refund of the current period already paid, and the store’s data is then deleted 48 hours later. To stop paying while keeping your size charts, use “Switch to the Free plan” instead.

Roles come from your Heylio account: Owner and Administrator can change everything; Agent can view everything, without changing anything (editing buttons are hidden, and a banner reminds them).

Someone who opens HeyFit from the Shopify admin, without a Heylio account, has the Administrator role for that store only.

Not on our servers. The measurements entered are used to compute the recommended size, then our servers discard them: they never store them. HeyFit only keeps an anonymous record of each recommended size, and of the size chosen next, to measure the guide’s effect.

So that your customer doesn’t have to enter them again on your other products, the guide keeps them in THEIR browser, on their device, if they tick the “Remember my measurements on this device” box. It is unticked by default: without their consent, nothing is kept. This copy stays on their device (neither HeyFit nor you can read it); “Clear my measurements” deletes it, and it is deleted automatically after one year.

Everything is detailed in the privacy policy: app.heyfit.app/privacy.

HeyFit’s access to your store is cut immediately. 48 hours later, all of the store’s data (size charts, assignments, returns, statements) is deleted, unless you have reinstalled HeyFit in the meantime.