How to create a size chart for Shopify products
Turn trusted measurements into a product-page size chart that explains what was measured, works in both units, and stays readable on mobile.
A supplier sends a spreadsheet with XS through XL, three measurement columns, and no explanation of how the numbers were taken. It looks like a finished size chart. It is really a set of unanswered questions.
Before placing those numbers on a Shopify product page, establish what each column describes, where the tape should sit, and whether the values refer to the shopper or the finished product. Formatting comes after meaning.
Choose one trustworthy source
Begin with the manufacturer specification, pattern measurements, or a checked internal worksheet. Do not quietly combine a supplier's bust values with a second source's waist values because one table has a gap. Different brands and product lines can use the same size labels for different dimensions.
Give the chart an internal owner and a revision date. When a vendor updates a pattern, the team needs to know whether the product page still reflects the version being packed in the warehouse.
Write the measuring method before the table
“Bust” is not enough on its own. For body measurements, say where the tape passes and whether it should be snug or relaxed. For a garment, say whether it is measured flat and whether a half-width value needs to be doubled to compare with body circumference.
Keep the method short enough to read beside the table. If a product needs a longer illustrated guide, link to it, but leave the essential distinction on the product page. A shopper should not need to leave the size decision just to learn what the numbers mean.
Label the subject, the unit, and the method. “Garment chest, measured flat, cm” is much harder to misread than “Chest.”
Keep columns tied to a decision
The size label belongs first. After that, include the measurements that change which variant a shopper should choose. A coat may need chest and sleeve length; trousers may need waist, hip, and inseam. Adding every specification from a technical pack usually makes the choice slower rather than safer.
Use ranges only when they are genuinely how the size was designed. If two rows overlap, add a fit note explaining how to decide between them. Do not hide the ambiguity behind perfectly aligned cells.
Convert units once, then spot-check the result
Keep one unit as the source of truth and derive the other from it. Decide on a rounding convention before conversion, because inconsistent rounding can make adjacent ranges overlap or leave a small gap. Check the smallest, middle, and largest rows after conversion instead of assuming the entire table is fine.
Place the chart beside the size choice
On an Online Store 2.0 theme, an app block can be added, moved, previewed, and customized in the theme editor. Place the chart near the product's size selector, not at the bottom of a long description. Shopify notes that block availability depends on the theme and section, so confirm the intended product section accepts app blocks before treating setup as finished.
A short chart can sit inline. A large table can open from a descriptive button such as “Size chart” or “Find your measurements.” Either way, the shopper should be able to return to the variant selector without losing the size they were considering.
Read it on the narrowest screen you support
Test a real product with long headings and the maximum number of columns. The size label should remain easy to follow while measurement columns scroll, text should not shrink into illegibility, and the unit control should not push the table wider than its container.
Finish by asking someone unfamiliar with the worksheet to choose a size and explain what one number means. If they have to guess whether it describes their body or the product, the chart is not ready yet.