Heart Rate Calculator Age Weight

Heart Rate Calculator (Age & Weight)

Calculate your maximum heart rate and target training zones

Measure while sitting quietly for 5 mins.

Male Female

Your Fitness Profile

Estimated Max HR 0 BPM

Heart Rate Reserve 0 BPM

Training Zone	Intensity	BPM Range

function calculateHeartRate() { var age = parseFloat(document.getElementById('calcAge').value); var weight = parseFloat(document.getElementById('calcWeight').value); var resting = parseFloat(document.getElementById('calcResting').value); var gender = document.getElementById('calcGender').value; if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } if (isNaN(resting) || resting 120) { alert("Please enter a valid resting heart rate (typical 40-100)."); return; } // Formulas: Max HR (Fox Formula) var maxHR = 220 – age; // Heart Rate Reserve (Karvonen Formula) var reserve = maxHR – resting; document.getElementById('resMaxHR').innerText = Math.round(maxHR); document.getElementById('resReserve').innerText = Math.round(reserve); var zones = [ { name: "Very Light (Recovery)", min: 0.50, max: 0.60, color: "#e0e0e0" }, { name: "Light (Fat Burn)", min: 0.60, max: 0.70, color: "#fff9c4" }, { name: "Moderate (Aerobic)", min: 0.70, max: 0.80, color: "#ffecb3" }, { name: "Hard (Anaerobic)", min: 0.80, max: 0.90, color: "#ffe0b2" }, { name: "Maximum (VO2 Max)", min: 0.90, max: 1.00, color: "#ffcdd2" } ]; var tableHTML = ""; zones.forEach(function(zone) { // Using Karvonen formula: Target HR = ((Max HR – Rest HR) * %Intensity) + Rest HR var low = Math.round((reserve * zone.min) + resting); var high = Math.round((reserve * zone.max) + resting); tableHTML += ""; tableHTML += "" + zone.name + ""; tableHTML += "" + (zone.min * 100) + "-" + (zone.max * 100) + "%"; tableHTML += "" + low + " – " + high + ""; tableHTML += ""; }); document.getElementById('zoneTableBody').innerHTML = tableHTML; // Estimated Calories Burned per hour at 70% intensity var avgHR = (reserve * 0.70) + resting; var calPerHour = 0; if (gender === 'male') { calPerHour = ((-55.0969 + (0.6309 * avgHR) + (0.1988 * weight) + (0.2017 * age)) / 4.184) * 60; } else { calPerHour = ((-20.4022 + (0.4472 * avgHR) – (0.1263 * weight) + (0.074 * age)) / 4.184) * 60; } if (!isNaN(weight)) { document.getElementById('calorieNote').innerText = "Estimated burn at 70% intensity for your weight: " + Math.round(calPerHour) + " calories per hour."; } document.getElementById('hrResults').style.display = 'block'; document.getElementById('hrResults').scrollIntoView({ behavior: 'smooth' }); }

Understanding Your Heart Rate by Age and Weight

Target heart rate zones are essential for anyone looking to optimize their fitness, whether the goal is weight loss, cardiovascular endurance, or athletic performance. This calculator uses the Karvonen Formula, which is widely considered more accurate than simple percentage-based calculations because it factors in your Resting Heart Rate (RHR).

Why Weight and Age Matter

While age is the primary factor in determining your Maximum Heart Rate (MHR), your weight plays a significant role in metabolic cost. A heavier individual requires more energy (and thus more oxygen/heart effort) to move at the same speed as a lighter individual. By tracking heart rate relative to your weight, you can more accurately estimate calorie expenditure and ensure you aren't overstraining your cardiovascular system.

The 5 Training Zones Explained

• Zone 1 (50-60%): Very Light. Best for warm-ups, cool-downs, and active recovery.
• Zone 2 (60-70%): Fat Burn. Increases metabolism and fat utilization. You should be able to hold a full conversation.
• Zone 3 (70-80%): Aerobic. Improves lung capacity and heart strength. Conversation becomes difficult.
• Zone 4 (80-90%): Anaerobic. Increases speed and power. High intensity; lactic acid starts to build.
• Zone 5 (90-100%): Red Line. Maximum effort for short bursts. Used primarily by competitive athletes.

Practical Example

Imagine a 40-year-old individual weighing 80kg with a resting heart rate of 70 BPM.

1. Max HR: 220 – 40 = 180 BPM.
2. Heart Rate Reserve: 180 – 70 = 110 BPM.
3. Fat Burn Zone (60%): (110 * 0.60) + 70 = 136 BPM.

In this scenario, to stay in the "Fat Burn" zone, the individual should aim to keep their heart rate between roughly 136 and 147 BPM.

Important Disclaimer: These calculations are estimates based on standard physiological formulas. If you have a heart condition, are on blood pressure medication (like beta-blockers), or are starting a new intense exercise regimen, please consult with a healthcare professional before relying on these targets.

Frequently Asked Questions

How do I find my Resting Heart Rate?
The best time is first thing in the morning before getting out of bed. Place two fingers on your wrist or neck and count the beats for 60 seconds.

Does weight directly change my Max Heart Rate?
No, the biological limit of your heart (Max HR) is primarily dictated by age and genetics. However, weight affects how quickly you reach that max HR during activity.

What if I can't reach my calculated Max HR?
That is normal. The "220 – age" formula has a standard deviation of about 10-12 beats. Your personal maximum may be slightly higher or lower.