You will need
  • a dressmaker's cloth tape or ruler and tape.
To measure the size of the head , take a dressmaker's cloth tape and wrap it around the head. Inch position above the eyebrows and a half or two inches, slightly above the Pinna, so that it passed through the most projecting point on the head. Define the maximum circumference of the head. Measurement spend at least two or three times to make sure and specify size. Centimeter should fit the head quite tightly, but without tension.
If no tailor's centimeter, then cut and glue a paper strip of width 2?4 inches of such length that it can be wrapped around the head. Mark on it the beginning and the end circumference of the head. Remove the paper tape from the head and measure it with a ruler. Repeat the measurement two or three times. Instead of paper you can use a dense non-elastic band of tissue.
To measure the head in a stable sitting position, especially if it's the baby's head. Try in different dimensions a little bit to move the cm to determine through what point of the head, forehead and at what distance above the auricles is the maximum circumference of the head. Each time record the measured head, and then to find among them, the largest circumference.