How to Write Size Guides That Actually Reduce Returns

A size guide reduces returns when it tells shoppers how to measure themselves, how each garment is meant to fit, and which size to pick. A generic chart pasted onto every product page rarely does that, because numbers without context leave people guessing.

This guide walks through what to include, where to put it and how to check it is working. It suits online fashion retailers and independent tailors alike.

Why do size guides fail to reduce returns?

Most size guides fail for ordinary reasons. They are easy to fix once you spot them.

• One chart for everything. A fitted dress and an oversized hoodie do not follow the same rules.
• No explanation of how to measure. Shoppers do not know where the waist is meant to be measured.
• Mixed-up measurements. The chart does not say whether the numbers are body or garment measurements.
• Vague fit language. "True to size" means different things to different people.
• Hidden placement. A tiny text link at the bottom of the page gets missed.

Each of these leads to the same outcome. The shopper guesses, orders two sizes, and sends one back.

Should a size guide list body measurements or garment measurements?

Ideally both, clearly labelled. They answer different questions.

Type	What it tells the shopper	Best used for
Body measurements	Which size suits my body	The main size chart
Garment measurements	How big the item is laid flat	Fit-sensitive items like trousers, jackets and fitted tops

Body measurements help people choose a size. Garment measurements help them compare the item with something they already own and like.

Label every column. "Chest (body)" and "Chest (garment)" are far clearer than "Chest" alone. If you only have room for one, start with body measurements and add garment measurements on products where fit matters most.

How do you explain how to measure?

Keep the instructions short and plain. Put them right beside the chart.

1. Use a soft tape measure and stand relaxed.
2. Wear light clothing or measure against bare skin.
3. Measure chest at the fullest part, waist at the narrowest point, and hips at the fullest part.
4. Keep the tape snug but not tight.
5. Ask a friend to help if possible, since it is hard to measure yourself accurately.
6. Write the numbers down before choosing a size.

A simple diagram with labelled points helps a great deal. Add a line for inseam, sleeve length or shoulder width if the product uses them.

What fit information belongs on each product page?

The main chart can be shared across a range. Fit details should be specific to each product. Use this checklist.

• Fit type: slim, regular, relaxed or oversized
• Fabric and stretch: none, some or plenty
• Model height and the size they are wearing
• Item length, such as hem to shoulder or waist to ankle
• Rise for trousers and skirts
• Whether the item runs small or large compared with your usual sizing
• What to do between sizes, for example "size up if you prefer a looser fit"
• Any shrinkage after washing, if relevant

The model note is one of the most useful lines you can add. Something like "Model is 1.78 m and wears a medium" gives shoppers a real reference point.

Be honest in your fit notes. If a jacket is snug across the shoulders, say so. A shopper who is warned will usually choose well, and a shopper who is surprised often returns it.

How should you handle different regions and units?

If you sell across the UK, Nigeria and further afield, assume shoppers think in different systems. Some use UK sizes, some US or EU, and some are used to a tailor taking their measurements in centimetres or inches.

• Show centimetres and inches side by side, or add a simple toggle.
• Label which sizing system each column uses, such as UK, US or EU.
• Avoid relying on S, M and L alone, since brands define them differently.
• State your own sizing standard, so shoppers know what the numbers mean.

Clear labelling matters most for shoppers buying from abroad, who cannot easily judge how your sizes compare with local brands.

Where should the size guide go on the page?

Place it next to the size selector, not at the bottom of the page. A link or button that opens the chart in a pop-up works well, because shoppers can check it without losing their place.

Check it on a phone too. Wide tables that need sideways scrolling are frustrating, so keep columns few and text large enough to read. On Shopify, you can add a size chart as a pop-up, a collapsible tab or a product metafield, depending on your theme.

How can you tell if your size guide is working?

Your own data will tell you more than any general advice.

• Record a return reason every time, such as too small, too large or poor fit.
• Group returns by product to find the items where the guide is failing.
• Read customer messages that ask "what size should I get?" Each question points to missing information.
• Update the guide when a product's fit changes, and re-check it after each new batch.

If one style keeps coming back as too small, fix that product's fit note first. A one-line change often helps more than redesigning the whole chart.

Where does virtual try-on fit in?

A good size guide is the foundation, but some shoppers still want to see the item on a body like theirs. ZeDaq.ai provides an API and embeddable widget that adds AI Virtual Try-On and body sizing to product pages. It is available on the Shopify App Store. The widget speaks 10 languages and supports multiple currencies, which helps if your customers are spread across regions.

If you are a tailor or run a made-to-measure business, the same subscription includes measurement capture by auto-capture, voice-guided posing or manual entry. Clients do not need to install an app. You can also photograph old paper measurement books and turn them into digital client profiles. See ZeDaq.ai for tailors for details, or start free with the free plan or a 3-day trial, no card required.

FAQs

Do I need a size guide for every product?

You need one shared chart for each size system you use, plus product-specific fit notes. Fit type, model details and stretch should appear on every product page, even if the chart is shared.

What is the difference between body and garment measurements?

Body measurements describe the person wearing the item. Garment measurements describe the item itself, laid flat. Body measurements help shoppers pick a size, and garment measurements help them compare fit.

How often should I update my size guide?

Review it whenever you change a pattern, supplier or fabric, and after any run of returns for a single product. A regular check each season is a sensible habit.

Can tailors use size guides too?

Yes. Tailors can use one to help clients take their own measurements before a first fitting. Clear instructions and a diagram reduce errors, and they save time when you record the numbers in the client's profile.

Should I tell shoppers when an item runs small?

Yes, plainly and on the product page. A short, honest note such as "runs small, size up" prevents wrong orders and builds trust.