Sizing complaints and returns are one of the more frustrating categories of customer issue for POD sellers, mostly because they're largely preventable with a little extra clarity upfront — the size chart already exists, it's just usually underused.
The first thing worth understanding is that different garment brands run at genuinely different sizes, even at the same labeled size. A "large" from one brand your POD provider offers can run noticeably differently than a "large" from another brand, especially between unisex and women's-cut fits. If your platform lets you choose which specific blank garment brand fulfills an order, checking that brand's actual measurement chart (not just assuming "large is large") matters more than people expect.
Chest width versus body length is a distinction worth actually presenting to customers, not just linking to a generic size chart and hoping they interpret it correctly. A short, plain-language note — "this runs true to size in the chest but slightly longer in body length than a standard tee" — communicates more useful information in one sentence than a raw measurement table most shoppers skim past without really absorbing.
Unisex sizing is a specific point of confusion worth addressing directly if you're selling unisex-cut apparel to a majority-female customer base. A quick note like "this is a unisex cut — if you prefer a more fitted look, we'd suggest sizing down one size" prevents a specific, very common category of return before it happens, rather than customers guessing and getting it wrong.
If you have any actual customer feedback about sizing running large or small relative to the official chart, don't be afraid to include that directly in your listing, even informally ("a few customers have mentioned this runs slightly large — sizing down is an option if you prefer a snugger fit"). This kind of practical, lived-experience note builds more trust than a manufacturer's official chart alone, and it directly reduces returns from people who would've otherwise guessed wrong.
Lastly, if your POD platform allows it, include the actual flat measurements (chest width, body length in inches) directly in your listing images, not just as a linked chart — a simple size chart graphic embedded as one of your product photos gets seen by far more shoppers than a chart buried in a separate tab or external link.