Measuring arm circumference is a good way to keep track of progress during weight training or dieting. It is a simple process, and therefore can be done quite often. It is also a necessary task if you wish to tailor a shirt or jacket.
Wrap a tape measure tightly around your relaxed bicep, and record the measurement.
Flex your bicep and tightly wrap the tape measure around your flexed bicep. Record the measurement.
Wrap the tape measure tightly around your forearm, about halfway between your elbow and your wrist. Record the measurement.
Wrap the tape measure tightly around your upper arm. The tape measure should be just underneath your underarm. Record the measurement.