What numbers constitute high blood pressure?

A top number above 140 and a bottom number above 90 is considered high blood pressure at stage 1. Stage 2 high blood pressure begins when the top number is above 160 and the bottom number is above 100, as stated by the National Heart, Lung, and Blood Institute.

A normal blood pressure reading is a top number of 120 or less and a bottom number of less than 80. These are the correct readings for an adult; children's blood pressure is slightly different. It is important that people maintain their blood pressure in the normal range because if not, it can lead to serious conditions, according to the National Heart, Lung, and Blood Institute.