Buy it once, buy it right

1. The size chart beats the letter

A "medium" is a suggestion; the size chart is a fact. The one habit that changes online clothes shopping more than any other is taking two measurements — bust and natural waist, with a soft tape, over whatever you would normally wear — and checking them against the chart on the product page rather than the letter on the tag. Sizes drift by brand and by country of manufacture; centimeters do not lie.

When you are between sizes, the fabric decides. Woven fabric (a blazer, a non-stretch dress) has no give: size up. Knits and stretch denim recover: size down and let the fabric do the adjusting. Every review on this site notes which way the piece runs — that note is written from exactly this rule.

2. Stretch denim is bought snug

Stretch denim relaxes — roughly half a size over the first days of wear — and it does not shrink back in the wash. The correct fit on day one is snug but not tight: you should be able to pull the waistband an inch or two from your waist, no more. Bought true-to-size-comfy, a stretch jean is baggy at the knee by week two. Our Sidefeel straight-legs and the Gloria Vanderbilt Amandas both follow this rule; between sizes in either, go down.

3. Knitwear: the care label is the sizing prediction

Two things ruin knitwear fits: heat and hangers. Anything wool or wool-blend wants a cool wash and a flat dry — a hot tumble cycle shrinks it a full size, permanently. And drying on a hanger stretches the shoulders into points; flat-drying on a towel keeps the shape you bought. The dense knits on our list (VIISHOW, Trendy Queen) hold their shape better than fine gauges precisely because of their weight — but no knit survives a hot dryer, whatever the listing says.

4. Shoes: length first, width second, time third

Shoe fit has three dimensions and people check one. Length: a thumb's width between longest toe and the end of the shoe — and measure both feet in the afternoon, when they are at their largest, standing up. Width: if the widest part of your foot presses the upper sideways, no length trick fixes it; check whether the brand runs narrow (ours are noted in each review). Time: leather-look uppers relax over the first week of wear; buy for the relaxed state, not the day-one pinch.

The Athlefit boots run true in length and snug in width at first; the SERNIAL sneakers run slightly narrow — both notes are in their reviews, and both matter more than the size letter.

5. The returns habit that saves every purchase

Buying clothing online is a fitting process, not a lottery. Try the piece on the day it arrives, indoors, with the shoes and underlayers you will actually wear it with — and return immediately if it fails, before it sits in the closet losing its window. Keep tags on until you have worn it once at home. This one habit converts most "it didn't fit" disappointments into a correct second order, and it is why we never call a piece a sure thing without also telling you which way it runs.