Every listing lists real measurements taken flat, straight across — not a size label. Vintage sizing runs all over the place, so grab a tape measure and compare against something you already own and love the fit of.
Lay the item flat and buttoned/zipped. Measure straight across the waistband, just below the button, then double it.
From the top of the waistband straight down the outer leg seam to the hem.
From the crotch seam straight down the inner leg to the hem.
Lay the item flat. Measure straight across from one armpit seam to the other, then double it.
From the highest point of the shoulder seam straight down to the hem.
From the shoulder seam straight along the sleeve to the cuff.