# Blood Pressure Calculator

Determines mean arterial pressure and pulse pressure from systolic and diastolic measurements.

You can read more on blood pressure and the stages of hypertension in the text below the tool.

The blood pressure calculator uses the measured values of systolic and diastolic pressure to estimate, based on formulas, the mean arterial pressure (MAP), the blood pressure status (ranging from normal, pre-hypertension to hypertension stage II).

The two measurements are input in millimeters of mercury (mmHg), the first being the maximum pressure in the system while the second one being the pressure obtained in between beats.

The two formulas used are:

■ For mean arterial pressure: MAP ≈ [(2*DP) + SP]/3

■ For pulse pressure: PP = SP – DP

The hypo, normal, hyper -tension interpretation accounts for SP, DP and the following stages:

 Blood Pressure Status Systolic (mm Hg) IF Distolic (mm Hg) Min Max Min Max Normal Blood Pressure <120 and <80 Pre-hypertension 120 139 or 80 89 Stage I High Blood Pressure (Hypertension) 140 159 or 90 99 Stage II High Blood Pressure (Hypertension) 160 180 or 100 110 Hypertensive crisis (where emergency care is required) >180 or >110

Systolic pressure (SP)
Diastolic pressure (DP)
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Steps on how to print your input & results:

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

## Variables considered

Blood pressure is one of the widely measured vital signs (along with heart rate, respiratory rate and temperature) defined as the pressure applied by the circulating blood on the blood vessel surface. It is expressed in mmHg and as a rapport of SP/DP.

Systolic blood pressure is the maximum achievable pressure during heart contraction (heart beat).

Diastolic blood pressure is the minimum of the two values, achievable during the resting period between two subsequent contractions.

BP is controlled by the nervous and endocrine systems. Values lower than normal are classified under the term hypotension while values higher than normal are classified under hypertension.

## Blood pressure formulas

The mean arterial pressure is the average blood pressure during one complete cardiac cycle, meaning the pumping of the blood from the ventricle into the arteries during one contraction and the subsequent relaxation period.

MAP ≈ [(2*DP) + SP]/3

The pulse pressure is the difference between the systolic and the diastolic components of the BP. It can be translated into the force generated by each heart contraction. During rest PP is around 40 mmHg.

PP = SP – DP

## Blood pressure chart

The following introduces two ways in which the blood pressure values can be interpreted (based on the same intervals), in order to provide the patient with a cardiovascular status:

A) Blood pressure status table

 Blood Pressure Status Systolic (mm Hg) IF Distolic (mm Hg) Min Max Min Max Normal Blood Pressure <120 and <80 Pre-hypertension 120 139 or 80 89 Stage I High Blood Pressure (Hypertension) 140 159 or 90 99 Stage II High Blood Pressure (Hypertension) 160 180 or 100 110 Hypertensive crisis (where emergency care is required) >180 or >110

B) Blood pressure chart

 110 Hypertension 100 90 Hypertension Stage II 80 pre-Hypertension Stage I 70 Normal blood pressure 60 50 40 70 80 90 100 110 120 130 140 150 160 170

## References

1. Hall J. (2015) Guyton and Hall Textbook of Medical Physiology 13th ed. Elsevier Health Sciences.

2. Klabunde R. (2005) Cardiovascular Physiology Concepts. Lippincott Williams & Wilkins.

3. Caro CG. (1978) The Mechanics of The Circulation. Oxford [Oxfordshire]: Oxford University Press.

Specialty: Cardiology

System: Cardiovascular

Objective: Determination

Type: Calculator

No. Of Variables: 2

Abbreviation: BP

Article By: Denise Nedea

Published On: March 15, 2017

Last Checked: March 15, 2017

Next Review: March 9, 2023