Measure down the front, starting where your neck joins your shoulder. Bring the tape down your body to where you want the shirt to finish. This measurement will be the actual length of your shirt.

Measuring from the front, run the tape right under your armpits and around the back. Pull the tape snug, but not so that it cuts into you, and read off the measurement.

Measure around from the front of your stomach at the narrowest part of your waist. Pull the tape snug but not so that it cuts into you and read off the measurement.

Measure from the front around the broadest point of your hips. Pull the tape snug as before and read off the measurement.

Measure across the top of your shoulder blades from the point where your arm and shoulder meet; this will be the distance from one arm seam to the other (but measure your body, not an existing shirt). Follow the natural slope of your shoulders.

Your arm should be relaxed, not straight. Start from the end point you used when measuring your shoulders and bring the tape down, curving it behind your elbow, down your forearm to half way between your wrist bone and the knuckle of your little finger. This will be the actual length of the shirt sleeve, from the shoulder seam to the bottom of the cuff.

Measure around your neck at the broadest part. Not too tight - insert your index finger inside the tape for a comfortable fit. This will be the actual size of the shirt collar.