Stand upright with your arms relaxed at your sides
Wrap a flexible measuring tape around the fullest part of your chest
Keep the tape level across your back and parallel to the floor
Make sure the tape is snug but not tight
Breathe normally and do not hold your breath
Read the measurement at the point where the tape meets
Record the measurement in inches or centimeters
For the most accurate result, measure over bare skin or thin clothing
Repeat the measurement once or twice to confirm consistency