How to Get the Right Size When Shopping Online

Sizing is the single biggest reason online clothing orders get returned. A photo can show color, drape, and general silhouette reasonably well, but it can’t tell you how a garment will sit on your specific shoulders, waist, or hips — and unlike a fitting room, there’s no way to try before you buy. The good news is that most online sizing mistakes are avoidable with a handful of habits: measuring yourself properly, reading the size chart that actually belongs to the item you’re buying, understanding why “your size” isn’t a fixed number across brands, and knowing how to convert sizing across regions when a retailer ships from outside your country. None of this requires special tools or expertise — it just requires treating the size chart as more important than the size label.

Start with your own measurements, not your usual size

The most reliable starting point for online shopping isn’t “I’m usually a medium” — it’s a small set of body measurements taken with a flexible tape measure, ideally by someone else or in front of a mirror so the tape stays level. For tops and dresses, that generally means bust or chest (measured around the fullest part), waist (measured at the narrowest point, usually just above the belly button), and hip (measured around the fullest part, typically 7–9 inches below the waist). For bottoms, waist and hip matter most, along with inseam if the site lists pant lengths separately. For outerwear, add shoulder width and arm length if the chart calls for them.

A few habits make these measurements more accurate. Measure directly against skin or thin clothing rather than over a bulky sweater. Keep the tape snug but not compressed — it should sit flat against the body without digging in. Stand naturally rather than sucking in or puffing out, since a chart is built around a body in a relaxed, standing position. And measure more than once; if two attempts differ by more than half an inch, average them or try a third time. Once you have these numbers, write them down somewhere you’ll actually find again — a notes app, a spreadsheet, or even a sticky note — because you’ll use them repeatedly across dozens of future purchases, and remeasuring from scratch every time you shop is the single most avoidable source of sizing mistakes.

It’s worth remeasuring periodically rather than treating these numbers as permanent. Bodies change over months and years for all kinds of reasons, and a measurement taken two years ago may no longer match reality. A quick annual check-in keeps your baseline numbers useful instead of quietly out of date.

Read the size chart on the specific item, not a general brand chart

This is the step most shoppers skip, and it’s the one that matters most. Many retailers publish both a general brand-wide size chart and an item-specific chart, and the two can differ meaningfully — a stretch jersey dress and a structured woven blazer from the same brand may use different measurement ranges for the same labeled size, because the amount of “ease” (extra room built into the garment beyond body measurements) varies by fabric and cut. Whenever a size chart is available directly on the product page, use that one instead of a catalog-wide chart buried in a separate size guide page.

It also helps to understand what a size chart is actually measuring. Some charts list body measurements (the measurements of the person the garment is designed to fit), while others list garment measurements (the actual dimensions of the finished piece, laid flat and doubled where relevant). A garment measurement will typically be larger than the equivalent body measurement, because it includes ease for movement and comfort — a “40-inch bust” garment measurement is not meant for someone with a 40-inch bust; it’s meant to comfortably fit someone with a bust several inches smaller than that. If a page doesn’t specify which type of measurement it’s showing, look for context clues: instructions to measure your body and compare, versus instructions to lay a similar garment flat and measure it, usually indicate which convention is in use.

When your measurements fall between two sizes on a chart, the right call depends on the fabric and the fit you want. For rigid, non-stretch fabrics (structured cotton, denim without spandex, tailored wool), sizing up is generally the safer choice, since there’s no give to accommodate a snug fit. For stretch or jersey fabrics, sizing to your smaller measurement — or even staying in your normal size — is often fine, since the fabric itself provides the room a rigid fabric can’t. Fit descriptions on the product page (oversized, relaxed, fitted, true-to-size) are worth reading in combination with the chart rather than instead of it, since “oversized” from one brand can look dramatically different from “oversized” at another.

Vanity sizing and why “your size” isn’t fixed

Vanity sizing refers to the well-documented pattern of clothing sizes shifting looser over time relative to actual body measurements — a size 8 sold decades ago corresponds to noticeably smaller actual measurements than a size 8 sold today at many retailers. This happened gradually and inconsistently across the industry, which is part of why there’s no single universal standard size chart that all brands follow today, even within the same country. The practical result is that your labeled size is brand-specific information, not a fixed personal attribute — a medium at one retailer can measure closer to a small or a large at another, and both retailers can be using accurate charts that simply define “medium” differently.

This is also why relying purely on memory of what size you usually wear is a weaker strategy than checking the chart every time, especially for a brand you haven’t ordered from before or haven’t ordered from in a while. Sizing standards can also shift within a single brand over time as the company updates its size charts or changes manufacturers, so even a brand you’ve shopped from before is worth spot-checking against the current chart rather than assuming this season’s version fits identically to what you remember from a past order.

The most useful mental shift here is to stop thinking of your size as one number and start thinking of it as a lookup — a body measurement you compare against whatever chart is in front of you, brand by brand, style by style.

Converting sizes across brands and regions

Cross-brand conversion inside a single sizing system (all US sizes, for example) is really just the size-chart problem described above, repeated for each retailer. Cross-region conversion adds another layer, because different countries use entirely different labeling systems even when the actual measurements are similar. US, UK, EU, Australian, and Asian sizing systems all use different number or letter scales, and a retailer’s chart usually needs to be checked for which system it’s actually displaying — a “10” on a UK-based site is not the same as a US “10,” even though both look identical on the label.

A general (and only approximate) rule of thumb for women’s clothing is that UK sizes tend to run about two to four sizes larger in number than the equivalent US size for the same body measurements — a US 8 is often close to a UK 12, for instance — but this offset isn’t perfectly consistent across categories or brands, so it should be treated as a starting estimate rather than a precise formula. EU sizing uses a different numbering scale entirely (often in the 34–50 range for womenswear), and Asian sizing systems frequently run smaller across the board relative to US or European charts for a given labeled size, meaning shoppers ordering from a site based in a different region may need to size up more than the standard conversion chart suggests.

Because these offsets vary by brand, category, and even individual style, the safest approach when shopping a retailer based in a different region is to ignore the label entirely and go straight to that retailer’s own measurement chart, converting your own body measurements (in inches or centimeters) directly rather than trying to mentally translate “my US size” into “their size.” Shoe sizing follows a similar logic — US, UK, and EU shoe size scales don’t align through simple arithmetic, and foot-length measurements in centimeters, when available, are usually more reliable than any label conversion.

Use photos and reviews as a second data source

Once you’ve checked the chart, product photos and customer reviews are the next-best source of fit information. Many product pages note the model’s height and the size they’re wearing (“model is 5’9” and wears a size 4“), which gives you a real reference point — if your height and proportions are noticeably different from the model’s, mentally adjust how the garment will likely drape on you rather than assuming an identical result. Brands sometimes flag directly on the product page that a specific style “runs small” or “runs large” or recommend sizing up or down for a particular cut; these notes are worth taking seriously since they usually reflect real return or feedback data specific to that item rather than a generic disclaimer.

Customer reviews, when available, are useful specifically for fit commentary — search or skim for mentions of the reviewer’s usual size, their measurements if given, and whether they sized up, down, or stayed true to size. A pattern across several reviews (multiple people saying a style runs small) is far more reliable than any single review, so weigh consistent feedback more heavily than one outlier comment. Photos submitted by other customers, where a site supports them, can also show how a garment actually drapes on a range of body types rather than only on the professional model.

Building a personal sizing reference

Because sizing is brand- and style-specific rather than universal, the most efficient long-term habit is to keep a simple running record: your body measurements, plus notes on which size worked for which brand and which category (a brand’s dresses might fit true-to-size while its jeans run small, for example). Over time this turns online sizing from a repeated guessing game into a quick lookup, since you’ll already know how a given retailer’s charts tend to run relative to your measurements before you even open the size guide.

Before finalizing any order where you’re uncertain, it’s worth running through a short checklist: Have you measured yourself recently, and do you have those numbers on hand? Are you looking at the item-specific chart, not just a general brand chart? Does the chart list body measurements or garment measurements, and have you accounted for the difference? If the fabric has little or no stretch, have you considered sizing up? And finally, have you checked the return policy in case the fit still doesn’t work out, since even careful measuring can’t fully replace trying something on. Combined, these habits won’t eliminate every sizing mistake, but they meaningfully cut down how often a package needs to go back.