Old size labels record a different body. A 1960s American size usually corresponds to a noticeably smaller set of measurements than the same number today. The label did not lie then and it does not lie now: there has simply never been a rule making the two comparable.
Sizing was never a binding standard, and still isn't
American women's ready-to-wear has no legally binding size definition. A 1958 National Bureau of Standards commercial standard set out body measurements for each size; it became voluntary in 1970 and was withdrawn in 1983, when brands began drafting to their own customer instead. What followed is vanity sizing: the same body gradually acquiring a smaller number as the decades passed.
Menswear is more stable and still not exact. A suit size is the chest measurement in inches, but a vintage size 40 is generally cut with more room through the chest and shoulders than a modern 40, because the pattern was drafted for a fuller armhole. The label is accurate. The cut is different.
What the label meant, against what it means now
| Label | Drafted for | Closest modern equivalent |
|---|---|---|
| US 12, early 1960s | A 32-inch bust and 25-inch waist | Roughly a modern US 2 to 4 |
| US 14, early 1960s | Much smaller than a modern 14 | Several sizes down today; measure |
| US 16, early 1960s | A 36-inch bust and 28-inch waist | Roughly a modern US 8 to 10 |
| UK 12, 1970s | Smaller than a modern UK 12 | A size or more down today; measure |
| Japanese M, 1990s | A narrower shoulder and body than a US M | Roughly a modern US S |
| Men's 40R, 1970s | A 40-inch chest with a fuller armhole | A modern 42R in most brands |
Two practical notes follow. A vintage garment in your nominal size will usually be too small, so one size up from your modern size is the honest starting point. And the discrepancy is widest in the decades with the strongest house styles, which is why 1950s and 1960s pieces read as dramatically smaller than the same nominal size today. Today's US sizes trace partly to a voluntary ASTM standard from 1995, which brands are free to ignore.
Measure the garment, then add the ease
A garment is measured flat and a body is measured around, so the two figures are not comparable until you allow for ease. A blazer cut to sit over a shirt is drafted with two to three inches at the chest, a coat with four or more, and a fitted dress with almost none. That is why the flat measurement of a well-fitting jacket is larger than your bust measurement, and should be.
The fast version: button the garment, lay it flat, measure across the chest an inch below the armhole, and double it. Compare that with a garment in your wardrobe whose fit you like, then read the shoulder seam to seam, because shoulders are the one area a tailor cannot enlarge.
Shoes, where the sizing really does mislead
Footwear is worse than clothing, because the systems differ by country and half sizes are not consistent. A US women's 8 is about a UK 6 and a European 38.5 or 39. A US men's 9 is about a UK 8 and a European 42. Differences of half a size between brands in the same system are routine, and an older leather shoe molded to somebody else's foot can feel a full size out until it re-forms.
Measure the insole inside the shoe, from toe to heel, and compare it with a pair you already own. That single figure sidesteps the conversions entirely, and it is the measurement most secondhand sellers will give you if you ask for it by name.
What a tailor can and cannot fix
Taking in is far easier than letting out. A garment can usually be reduced by up to two sizes, roughly four inches in total, if the seams are accessible. Letting out depends on seam allowance, and older garments typically hold about an inch per seam before the fold line shows. A lining doubles the work and the price.
Five measuring tools worth owning
All of these fit in a coat pocket or a drawer, and together they cost less than one mistake. Prices are shown only where we confirmed them on the brand or retailer page in Oct 2026.
Start hereSinger
Soft tape measure, 60 inch
The one tool that replaces every size chart, and it reads labels in three measurement systems. Buy two, because the first always disappears.
Check priceKomelon
Retractable tape measure with lock
Better than a soft tape when you are measuring a coat against yourself alone, or checking whether a shelf takes a folded knitwear stack.
Check price
Dritz
Seam gauge, 6 inch
A small rule with a sliding stop, used to check hem depth and seam allowance before deciding whether a garment can be let down or out.
Check price
John Lewis
Tracing wheel and tailor's chalk
Marks a hem or a take-in line on the inside of a garment without leaving a permanent trace, which is how you test a fit before committing.
Check price
Singer
Inseam and body tape set
A rigid inseam tape measures the inside leg without collapsing, and doubles as an insole measure. Trousers and shoes are where seller measurements go wrong most.
Check priceThe number to remember
One figure does most of the work: the flat chest or bust measurement, doubled. It survives sizing drift, vanity sizing, country conversions and a seller measuring in centimeters by accident. Learn your own shoulder width alongside it and vintage sizing stops being a gamble and becomes a filter you can apply from a photograph.
