What Should My Heart Rate Be When Exercising Calculator

Target Heart Rate Calculator

Calculate your optimal heart rate zones for specific fitness goals.

Leave blank for simple formula (220-Age), enter for Karvonen method.

Maximum Heart Rate (MHR): 0 BPM

Zone	Goal	Intensity %	Target Range (BPM)

What Should My Heart Rate Be When Exercising?

Understanding your heart rate is one of the most effective ways to monitor your workout intensity and ensure you are exercising safely and effectively. Whether your goal is weight loss, improved cardiovascular endurance, or peak athletic performance, training in the correct "zone" is crucial.

The Basics of Heart Rate Training

Your heart rate is measured in beats per minute (BPM). When you exercise, your heart beats faster to pump oxygenated blood to your working muscles. By keeping your heart rate within a specific range—your Target Heart Rate (THR) zone—you can optimize the benefits of your workout.

This calculator uses two primary methods to determine these zones:

• Standard Method (Fox Formula): This calculates your Maximum Heart Rate (MHR) simply as 220 minus your age. It is a general guideline used widely for beginners.
• Karvonen Method: This is more accurate as it factors in your Resting Heart Rate (RHR). By using your Heart Rate Reserve (MHR minus RHR), this formula tailors the zones to your specific fitness level.

Understanding the 5 Heart Rate Zones

Exercise intensity is generally categorized into five zones, based on a percentage of your maximum heart rate:

Zone 1: Very Light (50-60%)

Activity: Warm-up, cool-down, or active recovery.
Benefit: Improves overall health and helps with recovery. You can easily hold a conversation.

Zone 2: Light (60-70%)

Activity: Brisk walking, easy jogging, or cycling.
Benefit: Improves basic endurance and fat burning. This is often called the "Fat Burn Zone" because the body relies heavily on fat stores for energy.

Zone 3: Moderate (70-80%)

Activity: Moderate running, swimming, or dancing.
Benefit: Improves aerobic fitness and blood circulation. Moderate sweating occurs; speaking becomes slightly difficult.

Zone 4: Hard (80-90%)

Activity: Fast running, HIIT intervals.
Benefit: Increases maximum performance capacity and lactic acid tolerance. Breathing is heavy; conversation is difficult.

Zone 5: Maximum (90-100%)

Activity: All-out sprinting.
Benefit: Develops maximum speed and power. Can only be sustained for very short periods (seconds to minutes). Recommended for fit athletes.

How to Measure Your Resting Heart Rate

For the most accurate results using the Karvonen method in our calculator above, you need to know your Resting Heart Rate (RHR). The best time to measure this is in the morning, right after you wake up but before you get out of bed.

1. Find your pulse on your wrist (radial artery) or neck (carotid artery).
2. Count the beats for 60 seconds (or for 15 seconds and multiply by 4).
3. Repeat this for 3-4 days and take the average.

A typical RHR for adults is between 60 and 100 BPM. Well-trained athletes may see numbers between 40 and 60 BPM.

function calculateHeartZones() { // 1. Get Input Values var ageInput = document.getElementById("calc_age").value; var rhrInput = document.getElementById("calc_rhr").value; // 2. Validate Inputs if (!ageInput || isNaN(ageInput) || ageInput 120) { alert("Please enter a valid age between 1 and 120."); return; } var age = parseInt(ageInput); var rhr = 0; var useKarvonen = false; if (rhrInput && !isNaN(rhrInput) && rhrInput > 20 && rhrInput < 200) { rhr = parseInt(rhrInput); useKarvonen = true; } // 3. Calculate Max Heart Rate var maxHR = 220 – age; // 4. Prepare Logic for Zones // We will create an array of objects for the 5 zones var zones = [ { id: 1, name: "Very Light", color: "#9e9e9e", minPct: 0.50, maxPct: 0.60, desc: "Warm Up / Recovery" }, { id: 2, name: "Light", color: "#1976D2", minPct: 0.60, maxPct: 0.70, desc: "Fat Burn / Endurance" }, { id: 3, name: "Moderate", color: "#388E3C", minPct: 0.70, maxPct: 0.80, desc: "Aerobic Fitness" }, { id: 4, name: "Hard", color: "#F57C00", minPct: 0.80, maxPct: 0.90, desc: "Anaerobic / Performance" }, { id: 5, name: "Maximum", color: "#d32f2f", minPct: 0.90, maxPct: 1.00, desc: "Max Effort" } ]; var tableHTML = ""; // 5. Iterate and Calculate Ranges for (var i = 0; i 0) { minBPM = minBPM; // Slight adjustment not strictly necessary for general advice, keeping math pure standard } tableHTML += ''; tableHTML += 'Zone ' + z.id + '' + z.name + ''; tableHTML += '' + z.desc + ''; tableHTML += '' + Math.round(z.minPct * 100) + '% – ' + Math.round(z.maxPct * 100) + '%'; tableHTML += '' + minBPM + ' – ' + maxBPM + ' bpm'; tableHTML += ''; } // 6. Display Results document.getElementById("display_mhr").innerText = maxHR; document.getElementById("zones_table_body").innerHTML = tableHTML; var methodText = useKarvonen ? "Calculated using the Karvonen Formula (more accurate based on your resting heart rate)." : "Calculated using the Standard Formula (220 – Age). Enter a Resting Heart Rate for improved accuracy."; document.getElementById("method_explanation").innerHTML = methodText; document.getElementById("calc_results").style.display = "block"; }