Blood Pressure Calculator: Average Readings and Category

One blood pressure reading can be misleading: numbers vary from minute to minute and are often higher the first time you measure. Paste in a set of readings from your home monitor to get the average, its ACC/AHA category, and the mean arterial pressure and pulse pressure, with every reading listed separately. Classification uses the unrounded mean. A severe reading is flagged even when it is excluded from the average.

How to use this tool

1. Sit quietly for five minutes with your back supported, feet flat and arm resting at heart level, then take two or three readings a minute or two apart.
2. Type up to 300 readings, one per line as systolic/diastolic and optional pulse, for example 128/82 70. Remove dates and other annotations.
3. Tick “Leave out the first reading” if you follow the ESC/ESH method of averaging the last two of three.
4. Read the average and category, and check the table for any single reading that stands out.

Formula

Average = sum of readings ÷ number of readings; MAP = diastolic + (systolic − diastolic) ÷ 3; pulse pressure = systolic − diastolic

ACC/AHA categories: normal under 120 and under 80; elevated 120–129 and under 80; stage 1 hypertension 130–139 or 80–89; stage 2 hypertension 140 or higher or 90 or higher; severe hypertension above 180 and/or above 120. When the two numbers fall in different categories, the higher one counts. These are adult office-reading categories; home and ambulatory diagnostic thresholds can differ.

Example

Three morning readings of 132/84, 128/82 and 126/80 average 128.7/82, shown as 129/82 mmHg. The diastolic 82 is in the 80–89 band, so the average is stage 1 hypertension even though the systolic alone would be elevated. MAP = 82 + 46.7 ÷ 3 ≈ 98 mmHg, pulse pressure ≈ 47 mmHg and the average pulse is 70 bpm.