Taking your measurementsThe exact measurements you'll need will depend a little bit on the type of dress you're making. Generally, the more fitted your garment, the more measurements you'll need. Whatever measurements you take, the key is to make sure they are accurate. Ideally, have a friend help so you can be sure you're working from the correct numbers. Always take measurements wearing as few layers as possible. If you plan on wearing any kind of shapewear under the finished dress, make sure you have it on when you take your measurements, as anything that affects the shape of your body should also affect the shape of your dress. Take measurements with a dressmaker's tape—a flexible tape measure that's shorter and easier to use on garments than a quilter's tape. If you don't have a dressmaker's tape, you can use a length of grosgrain ribbon, or other flexible but non-stretch material. Mark each measurement on the ribbon as you take it, and then use a ruler or construction tape-measure to find the distance with the ribbon laid flat. The most basic measurements most patterns call for are of the shoulders, bust, waist, and hips.
ShouldersTo measure the shoulders, stand straight and tall with your arms at your sides. Make sure your head is up, since looking down at the floor can round your shoulders and add to the measurement. Have a friend measure across your upper back from the outside point of one shoulder to the outside point of the other.
Wearing the undergarments you plan to wear under your finished dress, measure around your bust at the fullest point. Have a friend make sure the tape stays parallel to the floor all the way around your body.
Regardless of whether the dress you're making has a dropped-waist dress or an empire waistline, take your preliminary waist measurement at your natural waistline. This is the narrowest point of your torso, often much closer to the bottom of the ribs than to your hip bones. To find this point, tie a piece of string around your waist, snugly, but not so tightly that it cuts into you. Bend and twist a few times to let the string settle. It will naturally find the narrowest part of your waist, and give you a landmark for taking other measurements. Measure around your waist at the string.
This measurement is something of a polite misnomer. It's not actually a measurement of the hips, like where mid-rise jeans sit, but of the wider part of your pelvis and fullest part of your posterior, almost at the tops of your thighs. Basically, this measurement is looking for the widest part of your lower body. Measure around your body, again making sure to keep the tape measure parallel with the floor the whole way around.
There are many, many other measurements that you may need to take to perfect your pattern, but it all depends on the style! One that may come in handy for choosing a pattern, however, it the high bust measurement. Like your regular bust measurement, wrap the tape measure around your chest, but instead of measuring the fullest part of your bust, measure the circumference of your torso above your bust. This may cause your tape measure to be angled up slightly, rather than perfectly parallel with the floor, but that's all right. Note this measurement for later.