How Secondhand Fashion Changed the Way We Think About Sizing

To find your size when buying secondhand or vintage, ignore the label and go by the seller's flat measurements. Lay the listing's numbers next to a garment you already own that fits the way you want, and compare like for like: chest to chest, waist to waist. The tag size is the least trustworthy thing in the listing because vintage labels are often decades old, clothing sizes have drifted larger over the years, and no single sizing standard has ever covered every brand and country.

That is also why the better resale listings now read like spec sheets. Sellers on platforms such as Depop, Vinted, Grailed, Poshmark, and Vestiaire Collective photograph a tape against the seams and list pit-to-pit, length, inseam, and rise, because numbers sell secondhand clothes and vague labels create returns. Your job as a buyer is to use those numbers the way they were meant to be used.

Why vintage and secondhand labels can't be trusted#

A size label is a promise the garment often can't keep, and with older clothing the gap is wider. Three things stack up against you.

Sizes have drifted larger over time#

Vanity sizing is a documented, gradual shift in ready-to-wear: over the decades, the body measurements assigned to a given number have grown, so a modern size is cut roomier than the same number was a generation ago. The label stayed put while the garment behind it changed. A vintage piece marked with a number you usually wear can read noticeably smaller than its contemporary equivalent for exactly this reason.

There is no single global standard#

Sizing systems differ by country and never fully agreed. US, UK, and EU women's numbers don't line up, Italian and French cuts differ from each other, and many Asian-market sizes run smaller than Western ones. Voluntary standards exist (ASTM body-measurement specs in the US, EN 13402 and ISO 8559 in Europe), but brands are not required to follow them and most cut to their own fit block. A label tells you which system a maker had in mind, not the finished dimensions.

The garment itself has changed#

Secondhand pieces have a history. Cotton and wool can shrink after years of washing, knits relax and grow, leather and denim mould to a previous owner. The original spec, even if you could find it, may not match the item in front of you now. The only reliable description is a fresh measurement of the actual garment, which is what a careful seller provides.

How to shop by measurements instead#

The method is the same one good sellers use in reverse: compare flat measurements to something that already fits.

Pick a reference garment you own#

Find a top, a pair of jeans, or a jacket in your closet that fits the way you want the new piece to fit. Lay it flat and measure it, or measure yourself with a soft tape. Write the numbers down once. Size AI captures body or garment dimensions with an iPhone if you would rather not wrestle a tape. Either way, you now have a target to compare against.

Which flat measurements to check, by garment type#

You don't need every number, just the ones that decide fit for that kind of garment. Flat means the garment is laid down and measured across one side; chest, waist, and hip are doubled to get the full circumference around the body.

Quick unit check: 1 inch is 2.54 cm. A flat chest of 20 inches (51 cm) equals a 40 inch (102 cm) chest measured around the body. For stretchy fabrics, look for both a relaxed and a stretched number, or ask for them.

Compare the listing to your reference, then decide#

Put the listing's flat numbers next to your reference garment's numbers. If the chest, waist, and length land within an inch or so of what fits you, the piece will fit similarly regardless of what the tag says. If the seller lists a label but no measurements, ask for the pit-to-pit and length before buying. A seller who measures is a seller you can trust.

Do vintage sizes run small?#

Often, yes, when you go by the label. Because of the size drift described above, a vintage garment marked with a number you normally wear was usually cut closer to the body than a modern garment with the same number. Older blocks also favoured a more fitted silhouette in some eras. None of that matters if you shop by measurements: a 38 inch chest is a 38 inch chest in any decade. When all you have is a label and you cannot get the tape numbers, size up rather than down.

Converting old or foreign sizes#

If a listing only gives a number from an unfamiliar system, treat it as a rough hint and confirm with measurements. Our international dress size chart and women's international size conversion chart show how US, UK, EU, and Asian numbers line up by body measurement, which is the only thing that translates cleanly across systems. For the full set, browse all conversion charts. Use them to narrow the range, then verify against the seller's flat measurements before you commit.

Frequently asked questions#

How do I know my size when buying secondhand?#

Go by the seller's flat measurements, not the label. Measure a garment you already own that fits well, or measure yourself once, and compare chest, waist, and length number for number. If a listing has no measurements, ask for pit-to-pit and length before you buy.

How do I convert a vintage size to a modern size?#

There is no exact decade-by-decade conversion, because sizing has drifted and no standard governed it. The reliable path is to convert by body measurement: take the garment's flat chest, waist, and hip, double the across-body numbers, and compare them to your own. A size conversion chart based on measurements gets you closer than matching old labels to new ones.

Do vintage clothes run small?#

Compared with a same-numbered modern size, they often do, because clothing sizes have grown larger over time through vanity sizing and some older cuts were more fitted. Measured in inches and centimeters, though, a garment is whatever it measures. When you only have a label, size up.

Which measurements matter most for resale clothing?#

For tops, chest, shoulder, and length. For bottoms, waist, hip, rise, and inseam. For jackets, shoulder and chest first, since the shoulder seam is hard to alter. These few numbers decide fit; the rest are nice to have.

Why do two items in the same size fit differently?#

Because the label points to a target body, not a finished garment, and every brand cuts to its own fit block. Two pieces tagged the same can differ by more than an inch flat. The flat measurement is the truth; the tag is a label.

What if the seller only lists a size, not measurements?#

Message them and ask for the flat pit-to-pit, length, and (for bottoms) waist, rise, and inseam. Most careful sellers will measure on request. If they won't, treat the listing as a guess and factor a possible return into your decision.

Measure once, shop with confidence#

The whole approach rests on one set of numbers: yours. Measure yourself, or a favourite garment, a single time and keep the figures where you can reach them. After that, every secondhand listing with real measurements becomes a quick comparison instead of a gamble. You can capture those numbers with a tape or with Size AI, the iPhone app that measures with the phone's LiDAR sensor. Then let the seller's tape do the talking, and ignore the label.