Blood pressure is written as a combination of two numbers, for example 120/80. The normal range for blood pressure is when the systolic number (written first) is less than 120 and the diastolic number (written second) is less than 80.Other People Are Reading.he normal range for blood pressure is when the systolic number (written first) is less than 120 and the diastolic number (written second) is less than 80. Other People Are Reading.