How to take body measurements
I hope that this page will answer any questions you may have about finding your size and providing measurements for the best fit possible. It is always easier to have a partner take your measurements for you, but it is totally doable solo, although a full length mirror will be very helpful. You can purchase a soft sewing measuring tape at any drug store for very cheap, or you can use a length of string and a ruler as well. You can take measurements in your underwear, or any fitted clothing; just don't take your measurements over a thick sweater or any clothing that will add significant volume.
Don't stress about being exact to the 1/8th of an inch, you can generally round to the closest 1/2 inch. You also do not need all of these measurements for every garment. For most tops the chest and front length are most essential, while for pants everything below the waist is pretty important.
Begin by finding a string, or a ribbon, or a piece of elastic and tying it around your waist. The tie around your body will most likely find the smallest circumference, but if that is not the case, you can use just above the bellybutton as a reference, or just decide where you like your waistbands to sit around your body. Keep this string (or whatever), on for the remainder of the measurements, as it will be needed for a reference point. Measure around this circumferene for your waist measurement.
Second, you will want to measure your chest. This will be around the fullest part of your upper body. You'll want to get your string or tape as level as you can (parallel to the floor), around at this fullest point. I would bring the two ends around the back and towards the front and gently shimmy it upwards to make sure you've got the fullest point, before bringing the ends around to the front to note the measurement.
Next up is the hips. This measurement is similar to the chest in that it should be the widest part of your lower body. You should again wrap from back to front and shimmy the tape so it's level and around your fullest point. Note the measurement.
Now you will measure your front length. Place the tape end at the center of the tip in your clavicle bone and run it straight down towards your belly-button to the tie that should still be around your waist. If you have a fuller chest, allow the tape to lay gently down your body, no need to pull it super tight.
Now things get a bit trickier if you're measuring yourself. This is where a full length mirror can come in handy. Place the end of the tape at the tie around your waist and allow it to drop down to the floor. You may have to shift your legs around a bit to get the tape lying as close as you can to the body down your hip. If you're ordering pants, note the measurement that is closest to the ground, always rounding down numerically instead of up. If ordering shorts, you can choose the length at which you want your hem to lay.
Inseam is also tricky and the mirror will help. Place the end of the tape between the legs, ideally where it will be comfortable for the crotch of your pants to fit. The garments are designed to be fitted, so get close, but keep it comfortable. Again, let the tape fall to the floor and do a little dance until it's lying close to the inside of one leg. It will help to keep one leg straight up and down and swing one leg either forwards or backwards enough to see the measurement closest to where the tape hits the floor.
Okay, it gets easier from here on out! Step 7 is the crotch length. Place the end of the tape at the tie around your waist, centered around your bellybutton, and swing the loose end down between your legs and back up the other side around your butt. Again you'll want the tape to feel fitted but not super tight. You'll take the measurement where the tape meets the tie around your waist in the back.
Almost there! Next up is your thigh. Measure around and level. The height at which to measure is basically in the middle between your hip and knee. This should not be the fullest point, but should be around the muscular part of your thigh.
Lastly, you'll take a measurement around your knee. Just make sure to bend your knee when you take the measurement, because it's important for ease of movement.