121/77 is a normal blood pressure. You may refer on the American Heart Association blood pressure chart below.
A blood pressure reading has a systolic (top number) and diastolic (bottom number).
Systolic measures the pressure in the arteries when the heart beats (when the heart muscle contracts). Diastolic measures the pressure in the arteries between heartbeats (when the heart muscle is resting between beats and refilling with blood).
Blood pressure rises with each heartbeat and falls when heart relaxes between beats. While BP can change from minute to minute with changes in posture, exercise, stress or sleep, it should normally be less than 120/80 mm Hg (less than 120 systolic AND less than 80 diastolic) for an adult age 20 or over.
Tip! Check out 13 Ways To Lower Blood Pressure Naturally, shared by Prevention.