6,900 size estimates, zero tape measures: one month of sizing at a streetwear label

Every fashion shopper hesitates over two questions before buying. Will it suit me? And will it fit me?

The first is visual. The second is numeric, and most product pages answer it badly: a table of centimetres, a tape measure nobody has to hand, and a guess. When I ran Heritage Fashion, "does this run small?" was the question in our inbox more than any other.

 

Now picture the hardest version of that question. A unisex streetwear label where every style runs XS to 2X, so half your shoppers are converting from sizes they normally buy. The bestsellers are heavyweight oversized hoodies, so even people who know their size wonder whether to size down. And many pieces drop as pre-orders, so a wrong size means weeks of waiting followed by a return.

That's the store these numbers come from. They asked us not to name them, which is fair. The figures below come straight from their AIFrame dashboard for September 2026.

One month, one streetwear label

• About 6,900 size estimates completed by shoppers
  
  
• About 960 Fit Profiles saved, from height, weight and age alone. No tape measure.
  
  
• 438 purchased items bought by shoppers who had seen a size recommendation or the Size Chart before checkout

That's the "will it fit?" question being answered at scale, by real shoppers, on a store where fit is hard to judge.

Why "no tape measure" changes everything

There's a simple principle behind this. A shopper's certainty, and their willingness to act, drops with every input you ask of them. Asking for chest, waist and hip measurements means finding a tape measure, measuring correctly and trusting the result. Most people won't. Everyone knows their height, weight and age by heart.

AIFrame turns those three numbers into estimated chest, waist and hip measurements. It uses regression models fitted on ANSUR II, a public body-measurement dataset of around 6,000 people. Typical error is 2.5 to 4.8 cm. That's small enough to pick the right row in a Size Chart, where sizes are usually 4 to 6 cm apart. The estimate only uses what the shopper types in. We never infer body attributes from a photo.

Why 960 is the number we watch

Saving a Fit Profile is opt-in. The shopper ticks a consent box, and if they don't, the estimate stays in their browser session and nothing is stored. About 1 in 7 shoppers who ran an estimate chose to save one.

That matters most on a store built around drops. A shopper who saves a profile on one hoodie sees their recommended size on every product that has a Size Chart, including the next drop. They enter their details once and see their size everywhere.

It works because the sizing blocks were placed

This is the part I want every merchant to take away.

Sizing in AIFrame used to live inside the Virtual Try-On flow, so only shoppers who opened try-on ever saw a size recommendation. Most never did.

So we moved sizing onto the product page itself as two theme blocks. Sizing assist sits between the size picker and Add to cart and offers "Estimate my size". Size Chart link sits next to the size options. They show up exactly where the merchant puts them in the theme editor. If they aren't placed, they don't appear, because we deliberately don't inject things into your theme.

This label placed both blocks right where shoppers choose between S, M and L. That single decision is why the numbers above exist.

A decent size answer that every shopper sees beats a perfect one that nobody finds.

What the 438 means, and what it doesn't

We count a purchased item when the shopper saw a size recommendation or the Size Chart in the 30 days before buying. That shows sizing reached people at the moment they were deciding. It doesn't prove that every one of those sales happened because of it.

The next questions are the ones that matter most: did shoppers buy the size we recommended, and did size-related returns go down? AIFrame tracks both. We'll only publish return figures once enough orders are old enough to be returned and the sample is large enough to mean something. With pre-orders, that takes a little longer.

Try it on your store

1. Install AIFrame from the Shopify App Store and create or import your Size Chart.
   
   
2. In the theme editor, add the Sizing assist block between your size picker and Add to cart.
   
   
3. Add the Size Chart link block next to your size options.

The Size Chart is included on the Free plan. The size estimate and Fit Profile start on Starter. Install AI Frame now.