A customer knows their waist measurement. Your product page has a size chart. An AI tool says “Buy Large.” That sounds like a complete answer—until you ask what the chart actually measures.
Is the number a body circumference, the width of a garment laid flat, or a suggested range supplied by the manufacturer? Those labels change the question you are trying to answer.
Before improving the wording on a Shopify product page, make the underlying sizing information understandable. Here is a practical review you can run without inventing a fit recommendation.
Start with the meaning of the measurement
Body measurements describe the person, such as a circumference around the waist or hips. Garment measurements describe the item itself. A garment table might give a flat width, a circumference or a length, so the heading needs to say which one it uses.
A label such as “waist: 32 cm” leaves too much open. You need to know what was measured, where the tape was placed and whether the garment was relaxed or stretched. The number alone does not resolve those questions.
Keep the supplier’s measurement instructions with the source chart. If they are missing, ask for clarification before turning an ambiguous column into customer advice.
A simple example: arithmetic is not a fit test
The numbers in this section are fictional teaching examples. They are not ERVALO product specifications or a size recommendation.
Imagine that a chart lists a garment’s relaxed flat waist width as 32 cm. Doubling that width gives a nominal circumference of 64 cm for this simplified example. A customer reports a body waist circumference of 74 cm.
That comparison identifies a difference between two measurements. It does not establish whether the garment is suitable for the person. You still need product-specific information about the measurement method and the intended fit, including any relevant stretch guidance.
You also cannot assign the letter L from these numbers alone. A size label must be connected to the correct product’s verified chart. Do not replace a missing connection with a confident sentence.
Build a small source sheet before asking AI
Collect the information you can verify in one place. Keep unresolved questions in a separate column so they remain visible during writing.
| Information | What to establish |
|---|---|
| Product and variant | Which exact item and version does this chart describe? |
| Measurement type | Does each column describe a body, a flat garment or a garment circumference? |
| Unit and method | Are values in centimetres or inches, and how were they measured? |
| Condition | Are garment measurements relaxed, stretched or otherwise specified? |
| Fit guidance | What product-specific recommendation has the supplier actually provided? |
| Source and date | Where did the information come from, and which version did you check? |
If two supplier documents disagree, retain both and ask which one applies to the item you sell. Publishing a cleaner-looking table does not resolve conflicting source data.
Make the chart useful beside the size selector
The shopper should be able to identify the relevant chart while choosing a size. Give it a clear name, such as “Body measurements in cm” or “Garment measurements in cm,” only after confirming that description is accurate.
Explain the measuring method in a short note. Keep the units visible, and use the same size labels as the product options. On a phone, check that a person can read a complete row without losing the connection between its heading and values.
Shopify documents one way to attach a product-specific chart through a page-reference metafield and a pop-up. Its size-chart tutorial also notes that a pop-up label can appear without referenced page content. Whatever method your theme uses, open the chart on each relevant product and verify the destination.
A working pop-up is one check. The accuracy of its measurements is another. Record both rather than treating a successful click as approval of the sizing information.
Use AI to flag gaps before it writes advice
Give the model the chart, its measurement instructions and the source sheet. Ask it to identify uncertainty before producing customer-facing wording:
Review this product’s sizing information using only the supplied sources. For each measurement, identify whether it refers to a body, flat garment width, garment circumference or length. If that is unclear, mark it unknown. Check units, size labels and conflicts between sources. Keep calculated values separate from supplied facts and show the formula. Do not infer stretch, comfort, compression or a recommended size from missing information. Return an editor checklist, questions for the supplier and a short size-guide draft containing only confirmed facts.
Read the answer against the documents. If the model calls a measurement a body circumference without evidence, reject that interpretation. If it silently converts units or changes a size label, make the change explicit before considering it.
The same rule applies to the rest of the page: a fluent sentence still needs support. Our guide to checking AI product descriptions covers that wider review.
Keep both languages attached to the same facts
For a bilingual store, compare the chart title, units, size labels and measuring instructions in both languages. A translation should preserve what a measurement describes.
Use one approved source sheet for the two versions. When a supplier corrects a value or instruction, review both language versions and any size-chart images that repeat the information.
A useful test is to ask someone to explain what one row means without help. If they cannot tell whether to measure their body or a garment they own, the instructions need another pass.
Before you publish the next size guide
- Confirm that the chart belongs to this product.
- Name the measurement type and unit.
- Check the measuring method and any stated tolerances.
- Resolve conflicting values with the source.
- Keep unsupported fit recommendations out of the copy.
- Open and read the chart on mobile and in each language.
- Record what you verified and what still needs an answer.
The goal is to give the customer information you can explain and support. A size recommendation can wait until the product-specific evidence supports it.
What is hardest to establish in your supplier’s size chart: the measurement type, the units or the fit guidance? Share the missing detail in the comments.
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Subscribe for Shopify checks and AI workflows from Storefront Experiments. For more prompts you can adapt to your own verified information, read the subscriber Ecommerce Prompt Playbook.
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