"It didn't fit" is a return reason you can do something about before the order is placed. A clear size guide helps shoppers choose correctly, and a vague one sends them guessing or ordering two sizes. This guide covers what a useful size guide contains, where to put it, and how to keep it accurate.
Why generic charts fail
A chart that says S, M, L with a single chest measurement tells the shopper very little. Sizes vary between brands and often between products from the same brand. A guide helps when it describes this product, in measurements the shopper can check at home.
- Too generic: One chart for the whole store
- Too thin: Letter sizes with no measurements
- Unclear basis: No indication whether numbers describe the body or the garment
What a good size guide includes
Give shoppers enough to compare your product with something they already own or with their own measurements. Every row and column should be labelled, with units.
- Measurements per size: The points that matter for the product, such as chest, waist, hip, inseam or foot length
- Body or garment: State which one the numbers describe
- Units: Inches and centimeters, if you sell to both audiences
- How to measure: A sentence per measurement on where to place the tape
- Fit description: Slim, regular, relaxed or oversized
- Model reference: The model's height and the size they are wearing
- Between sizes: A plain recommendation to size up or down
Where to put it
A size guide works when the shopper sees it at the moment they choose a size. Put the link beside the size selector, not at the bottom of the page.
- ✅ Link or button next to the size options
- ✅ Opens on the page, so the shopper doesn't lose their place
- ✅ Specific to the product or product type
- ❌ A separate page reached through the footer
- ❌ An image of a table that can't be read on a small screen
It isn't just clothing
Any product where dimensions decide whether it works needs the same treatment. Furniture, bags, rings, phone cases, pet products and replacement parts all generate returns when measurements are missing.
- Furniture and decor: Width, depth and height, plus what fits inside or under
- Bags: Dimensions and an example of what they hold
- Rings and jewelry: How to measure at home
- Parts and accessories: The exact models they are compatible with
Use your returns to fix the guide
Your return reasons and reviews tell you where the guide is wrong. If a product keeps coming back as too small, the chart or the fit note needs correcting.
- Runs small or large: Say so on the page, next to the size selector
- One size returned more than others: Re-measure that size
- Repeated questions before purchase: Add the answer to the guide
For the rest of the page, see the product page checklist.
Doing this at scale
ConvertLens scores every product page from 0 to 100 against a conversion rulebook that includes specs alongside title clarity, scannability, images and trust. AI drafts before and after rewrites of weak sections from the page's own copy, you approve each change, and changes are logged and reversible. See ConvertLens.