How to answer “what size am I?” on Shopify from your own size chart

"What size am I?" comes right before the buy button for clothes and shoes, and a shopper who can't get an answer may simply not order. An AI assistant can answer it at any hour, but only from what you give it: your own size chart, your fit notes and your stock. Below: how to prepare the chart so an assistant reads it correctly, how to connect it in ChatPal (we make it), and where an assistant stops and a fit-prediction tool starts.

Size questions customers ask

Sizing messages come in a few flavours, and each one needs something different from you:

The assistant has no other brand's chart, so "I'm a medium everywhere else" can't be answered honestly by comparison. Tell it to ask for measurements instead, as shown in the setup below.

Size chart apps vs an assistant

Size chart apps and an assistant solve different halves of the problem, and you can run both from the same chart.

Fit finders vary. SizeFit, for example, suggests a size from a couple of measurements on its Pro plan at $14 a month (checked 13 October 2026). If true fit prediction matters to your returns, a dedicated tool is the right buy; the assistant is for answering the question where it's asked.

Preparing your size chart

An assistant reads text. A chart that looks fine to a person can still be useless to it, so follow five rules:

1. Text, not an image. Images are stripped when ChatPal reads a page, so a chart saved as a picture doesn't exist for the assistant.
2. One chart per collection or brand, with a title that says which: "Size guide: women's dresses".
3. Body measurements, labeled as such, with both units in every row.
4. Ranges written in full, "36 to 37" or "36-37", not a single number.
5. Fit notes under the chart, in plain sentences.

Here is a chart in that shape:

Size guide: women's dresses (body measurements)

Fit notes: True to size. Between sizes, size up in the linen dresses (no stretch) and size down in the jersey ones. Our model is 5'8" (173 cm) and wears S.

Garment measurements, such as the length of one dress, belong in that product's description, along with a line like "Sizing: see Size guide, women's dresses". The description travels with the product in your catalog, so the assistant has both together.

Setting it up

1. Connect your store. In ChatPal, go to Integrations, then Shopify, type your .myshopify.com address in Store address and click Connect Shopify. ChatPal keeps a read-only copy of your catalog, sizes and stock included, and Shopify changes usually reach it within minutes. The Shopify setup guide walks through the whole connection.
2. Publish each chart as a page. In your Shopify admin, go to Online Store, then Pages, and click Add page. Put the chart in the page content as a table of text, add the fit notes, keep it Visible and save.
3. Give the pages to the assistant. When you connect, ChatPal reads your store's own pages, but check: open Configuration, then the Links tab. If a size guide isn't listed, paste its address, tick Single page only and click Add Link. To check what the assistant will read, choose Edit in the ⋮ menu next to the link; the rows should be there as text.
4. Or upload it as a file. A Word or plain-text chart works under Files with Upload files. Tables in PDFs sometimes come out jumbled, so check the extracted text the same way.
5. Write the sizing rules. In the Instructions field on the Basic tab, add something like: "For size questions, ask for bust, waist and hip measurements if the shopper hasn't given them. Compare them with the size guide for that product's collection, name the size and the row you used. Between sizes, follow the fit notes. If someone gives a size from another brand, ask for measurements instead. Never promise a perfect fit; mention that exchanges are free within 30 days." Use your own exchange terms.
6. Test it. Open Playground and ask the questions from the table above with your own products.

When you change a chart, edit the page in Shopify and choose Reindex in the ⋮ menu next to its link. Your catalog syncs itself; a page is read again when you reindex it. The same rules apply to the rest of your store's answers, covered in the FAQ page guide.

Example conversation

Here is the exchange you're setting up, written for this guide with the chart above, not a recorded chat:

Shopper: I'm 36 bust and 30 waist. Which size in the Marlow linen dress?

Assistant: By our size guide for dresses, a 36-inch bust and a 30-inch waist are both in size M (bust 36 to 37, waist 29 to 30). The Marlow is linen with no stretch, and our fit notes say to size up if you're between sizes. You're inside M on both, so M should fit; choose L if you like room at the waist. M is in stock in Sand and sold out in Black.

If the shopper asks to see it, a product card follows. On your storefront, because the dress comes in several sizes and colors, the card offers Choose options before Add to cart, and once the shopper has settled the size, they can ask the assistant to add it. On WhatsApp, Instagram and Messenger they get the card with a link to the product instead.

Run this exact test in the Playground with one of your own products and a measurement that sits between two rows. That's where a weak chart or missing fit note shows up first. Click Why this answer? under the reply to see which chart it used.

Limits

• It reads your chart; it doesn't predict fit. No body-shape model, no learning from returns. A wrong chart gives a confident wrong size.
• In stock or not, not how many. It doesn't give exact stock counts.
• No catalog-wide size filter yet. It checks a size on products it has found, but "show me every dress you have in M" isn't a filter it can run across the whole catalog.
• Cart only on your storefront. Adding a size to the cart from the chat works in the Shopify storefront widget, not in WhatsApp, Instagram or Messenger.
• It can't see images of charts. Keep the chart as text, on a page or in a file.

Each reply counts toward your monthly messages, your Playground tests included: 100 on Free, 500 on Starter at $20 a month (plans, checked 13 October 2026). For everything else a store's assistant should answer or hand to you, see the customer service chatbot guide for online stores.

If you already have a size guide page, you're most of the way there. Connect the store on the free plan, check the guide reads as text on the Links tab, and ask the Playground a between-sizes question for your best seller.