This BP Rate Calculator is designed to help you interpret your blood pressure readings quickly and accurately. Blood pressure is the force of your blood pushing against the walls of your arteries. Understanding the two numbers in your reading—Systolic and Diastolic—is crucial for maintaining cardiovascular health.
Important: This tool is for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician.
The Two Key Numbers
Your blood pressure reading consists of two numbers, typically written as a ratio (e.g., 120/80 mmHg):
Systolic Pressure (Top Number): This measures the pressure in your arteries when your heart beats. It represents the maximum pressure exerted during contraction.
Diastolic Pressure (Bottom Number): This measures the pressure in your arteries between beats. It represents the resting pressure when your heart fills with blood.
How is Blood Pressure Categorized?
Based on guidelines from the American Heart Association (AHA), blood pressure categories are defined as follows:
Normal: Systolic less than 120 AND Diastolic less than 80.
Elevated: Systolic 120-129 AND Diastolic less than 80.
High Blood Pressure (Stage 1): Systolic 130-139 OR Diastolic 80-89.
High Blood Pressure (Stage 2): Systolic 140 or higher OR Diastolic 90 or higher.
Hypertensive Crisis: Systolic higher than 180 and/or Diastolic higher than 120.
What is MAP (Mean Arterial Pressure)?
The calculator also computes your Mean Arterial Pressure (MAP). While your systolic and diastolic numbers show the extremes, MAP represents the average pressure in your arteries during one cardiac cycle. It is considered a better indicator of perfusion (blood flow) to vital organs than systolic pressure alone.
A normal MAP range is typically between 70 and 100 mmHg. If the MAP drops below 60 mmHg for an extended period, vital organs may not receive enough oxygen.
What is Pulse Pressure?
Pulse Pressure is the difference between your systolic and diastolic readings. For example, if your BP is 120/80, your pulse pressure is 40. Generally, a pulse pressure greater than 60 mmHg is considered a risk factor for cardiovascular disease, often indicating stiffness in the major arteries.
function calculateBP() {
// 1. Get input values
var sys = document.getElementById('sysInput').value;
var dia = document.getElementById('diaInput').value;
// 2. Validate inputs
if (sys === "" || dia === "") {
alert("Please enter both Systolic and Diastolic pressure values.");
return;
}
sys = parseFloat(sys);
dia = parseFloat(dia);
if (isNaN(sys) || isNaN(dia) || sys <= 0 || dia = sys) {
alert("Systolic pressure must be higher than Diastolic pressure.");
return;
}
// 3. Calculate MAP and Pulse Pressure
// MAP Formula: Diastolic + (1/3 * Pulse Pressure) OR (2*Dia + Sys) / 3
var map = (dia + (sys – dia) / 3).toFixed(1);
var pp = (sys – dia).toFixed(0);
// 4. Determine Category Logic (AHA Guidelines)
var category = "";
var desc = "";
var cssClass = "";
// Logic hierarchy: Check highest severity first
if (sys > 180 || dia > 120) {
category = "Hypertensive Crisis";
desc = "Consult your doctor immediately. This reading is critically high.";
cssClass = "status-crisis";
} else if (sys >= 140 || dia >= 90) {
category = "Hypertension Stage 2";
desc = "High Blood Pressure. Medical advice is recommended.";
cssClass = "status-stage2";
} else if (sys >= 130 || dia >= 80) {
category = "Hypertension Stage 1";
desc = "High Blood Pressure. Lifestyle changes or medication may be needed.";
cssClass = "status-stage1";
} else if (sys >= 120 && dia < 80) {
category = "Elevated";
desc = "Your reading is slightly above normal. Monitor closely.";
cssClass = "status-elevated";
} else if (sys < 120 && dia < 80) {
category = "Normal";
desc = "Your blood pressure is within the healthy range.";
cssClass = "status-normal";
} else {
// Fallback for uncommon combinations (e.g., low systolic but normal diastolic)
category = "Check Readings";
desc = "This combination is unusual. Please verify your numbers.";
cssClass = "status-elevated";
}
// 5. Update UI
var resultContainer = document.getElementById('result-container');
var resultBox = document.getElementById('mainResultBox');
var statusText = document.getElementById('statusText');
var statusDesc = document.getElementById('statusDesc');
var mapDisplay = document.getElementById('mapValue');
var ppDisplay = document.getElementById('ppValue');
resultContainer.style.display = "block";
// Reset classes
resultBox.className = "result-box " + cssClass;
statusText.className = "status-indicator " + cssClass;
statusText.innerHTML = category;
statusDesc.innerHTML = desc;
mapDisplay.innerHTML = map;
ppDisplay.innerHTML = pp;
}