01 · Product page
Léa hesitates. The button is right there, under the sizes.
“Find my size” shows on the product page, styled with your theme’s colors: as an app block, or through the automatic embed on older themes.
Size guide for Shopify
Help shoppers pick the right size, the first time.
HeyFit adds a “Find my size” button to your product pages: a recommended size with a clear explanation, selected in one click. With HeyReturn, the advice learns from your returns. And the price stays flat, with no per-order fees.
One shopper among many
Let’s follow Léa, torn between S and M.
CHEST 36.2 IN · WAIST 29.1 IN · FIT: REGULAR
Léa’s journey, with HeyFit
02 · Guide open
Your chart, not a generic one.
The guide shows YOUR brand’s chart, in centimeters or inches as the shopper prefers, with a “how to measure” diagram for each measurement.
03 · Recommended size
Her measurements, her preferred fit. A size, and the reason.
Léa enters her measurements and says how she likes her clothes to fit. HeyFit recommends M and explains why, measurement by measurement. Without her measurements, her height, weight and age are enough for an estimated recommendation. Her measurements are not stored on our servers.
04 · Size selected
One click, and it’s the right variant.
“Select size M” picks M in the product page form. All Léa has left to do is add it to her cart.
05 · Advice adjusted
And when an item runs small, HeyFit learns it.
With HeyReturn, items returned as “Too small” are counted product by product. From 5 returns in the same direction, the recommended size shifts by one size, and the size from the chart stays displayed next to it, with the explanation.
Why HeyFit
Two differences, you can check in the app.
What HeyFit does, next to what most size guides for Shopify offer.
Advice that learns from your returns
With HeyReturn, from the same Heylio suite, “Too small” and “Too large” returns are counted product by product. From 3 returns in the same direction, the trend shows; from 5, the recommended size shifts by one size. Your own declaration always comes first.
A flat price, no per-order fees
A monthly subscription with an amount known in advance: no fee per order, no commission on your sales. Billed by Shopify, with your Shopify bill.
| Criterion | Most size guides | HeyFit |
|---|---|---|
| Size advice | A fixed chart: the advice stays the same, whatever your returns say | Learns from your returns with HeyReturn: the recommended size adjusts, item by item |
| An item that runs small | Up to you to spot it, then fix the chart | Spotted by your returns, or declared by you: shoppers see the recommended size and the reason |
| Price | Often tiered, by number of orders | A flat monthly price, no per-order fees |
Comparison based on the public plans of size guide apps on the Shopify App Store, in October 2026. A few custom-quoted solutions, built for large retailers, also learn from returns.
Example · fictional store Maison Lune
What HeyFit shows you, in numbers.
Here is what your HeyFit statistics could look like over 30 days.
ExampleIllustrative figures: Maison Lune is a fictional store. These are not results measured by HeyFit.
1,240
sizes recommended
The number of recommendations shown to your shoppers, in your statistics, over 7, 30 or 90 days.
68%
of shoppers select the recommended size
The share of shoppers who click “Select size …” after the recommendation.
3
items flagged “runs small”
Your returns flag them in “What your returns say”: you confirm, and the advice adjusts.
The facts
And what is true for every store.
No more examples here: this is what HeyFit does, and you can check it in the app.
1
permission
Read your catalog, nothing else (read_products). HeyFit never changes your products, orders or customers.
0
customer data on our servers
Measurements are used for the calculation, then our servers forget them. The guide can keep them on the shopper’s device if they tick the box (unticked by default).
6
languages on your store
French, English, Spanish, German, Italian and Dutch, following the language the shopper sees.
All
themes, older ones included
As an app block on 2.0 themes, through the automatic embed on the others. Never two buttons.
The right size the first time can help reduce returns.
Note the “can”: we publish no figure on fewer returns until it is measured.
What HeyFit does
Everything shoppers need to order with confidence
Learning from your returns
With HeyReturn, size returns flag the items that run small or large, and the advice adjusts.
Your size charts
By hand, from a template, a CSV file or with AI (screenshot, web page, product description, reviewed by you); by product, collection, product type or for the whole store.
The “Find my size” button
On the product page, styled with your theme’s colors. Text, appearance and colors can be adjusted.
The size, explained
From measurements and preferred fit, measurement by measurement, with a confidence level. No measurements: estimated from height, weight and age.
The Heylio suite
HeyFit works with the Heylio suite
One account for every app. With HeyReturn, your returns for a size reason make the advice more accurate.
14-day free trial
The right size starts on the product page.
$19 per month · 14-day free trial. Billed by Shopify, with your Shopify bill. No commitment: switch back to the Free plan anytime, from Settings, without uninstalling.