Should I take medication based on this?

No — this is informational only. Hypertension diagnosis requires multiple readings on separate days, ideally including ambulatory or home monitoring. Discuss with your doctor.

My systolic is high but diastolic is normal.

Isolated systolic hypertension — common with aging as arteries stiffen. The category is set by whichever number is higher. Same treatment principles apply.

Blood Pressure Calculator

AHA blood-pressure category — normal, elevated, stage 1, stage 2, or hypertensive crisis.

Result

Reading

120 / 80 mmHg

Borderline

Hypertension Stage 1

CategoryHypertension Stage 1Borderline
Mean arterial pressureNormal range 70–10093 mmHg
Pulse pressureNormal range 30–5040 mmHg
RecommendationLifestyle changes; medication if 10-year cardiovascular risk is high.
Reference: Normal<120 / <80Healthy
Reference: Stage 1130–139 / 80–89Borderline
Reference: Stage 2≥140 / ≥90High risk

How to use this calculator

Sit quietly for 5 minutes before measuring; arm at heart level, feet flat.
Take 2–3 readings, 1 minute apart; record the average.
Avoid caffeine, exercise, and smoking for 30 minutes before measuring.
A single high reading is not a diagnosis — pattern over multiple days matters.

About this tool

Blood pressure is recorded as two numbers — systolic (peak pressure when the heart beats) over diastolic (resting pressure between beats). The 2017 American Heart Association guideline lowered the bar for hypertension diagnosis from 140/90 to 130/80, which doubled the diagnosed-hypertensive population overnight. The categories aren't arbitrary: each step up roughly doubles cardiovascular risk. A single high reading isn't a diagnosis — pressure varies hour-to-hour and is reliably elevated by stress, caffeine, full bladders, and the stress of being measured ("white-coat hypertension"). Get multiple readings on different days before drawing conclusions.

Frequently asked

Blood pressure is naturally variable. It rises with stress, talking, full bladder, recent caffeine, and even being measured (the "white-coat" effect). Variations of 10–20 mmHg over a day are normal.