Vintage clothing tends to fit a bit differently than modern clothing. It is is cut much closer to the body and for this reason it is essential that you allow enough room to move comfortably while wearing your vintage piece. I find myself forever telling people "Breathing is important!". Vintage garments should always be worn with care and consideration of their age.
Mid century clothing was also often designed to accentuate the hourglass figure and as a result you will find the waist lines tend to run small, this waspie figure can be attained with the right foundation garments, ie girdles, spanx and cinchers. Also if your measurements are off a little bit the situation can often be rectified by having the garment altered to fit you. Most online vintage stores are happy to answer any questions about available seam allowances, darts, and hem allowances before you purchase.
from Bella Hess catalog, 1940
Use a dressmaker’s tape measure. You can get one at your local fabric store.
Measure yourself over the undergarments you plan to wear under the vintage piece and not over your clothing.
BUST: measure over the fullest part of your bust while wearing a bra.
UNDERBUST: measure around the fullest part of your ribcage, about midway between your bust and waist.
WAIST: measure around the smallest point of your waist where it curves in.
HIP: measure around the fullest part of your hips. This is usually about 8"-9" below your waist.
SHOULDER TO WAIST: Measure from the top of your shoulder, where a normal shoulder seam would lie, down the front, following the curve of your bust.
LENGTH: measure from the top of your shoulder, where a normal shoulder seam would lie, down the front, to the point you want the garment to end at the hem.
ANOTHER HELPFUL HINT:
You can measure an item in your wardrobe that fits you well and is similar to the item you are wishing to purchase and compare the two.
Please remember the measurements in the listings are of the garment not you. This sounds like common sense but you would be surprised.
xOxO, LollyPOP Vintage