1. Relax your arm by your side.

2. Measure from the pointy edge of your shoulder (usually where the seams meet on your shirt).

3. Have the tape follow down your arm towards the back of the elbow.

4. Use the elbow to anchor the tape. Continue to measure down the back of the arm to the wrist or watch-line (where your shirt cuff naturally finishes).

5. Ensure the measuring tape remains in contact with your arm at all times.