How to Calculate Working Heart Rate

Working Heart Rate Calculator

Measured while sitting quietly, usually first thing in the morning.

50% – Very Light (Warm up) 60% – Light (Fat Burn) 70% – Moderate (Aerobic) 80% – Hard (Anaerobic) 90% – Maximum Effort (VO2 Max)

Your Working Heart Rate Is:

0 BPM

function calculateWHR() { var age = parseFloat(document.getElementById("age").value); var restingHR = parseFloat(document.getElementById("restingHR").value); var intensity = parseFloat(document.getElementById("intensity").value) / 100; if (isNaN(age) || isNaN(restingHR) || age <= 0 || restingHR <= 0) { alert("Please enter valid numbers for age and resting heart rate."); return; } // Karvonen Formula // 1. Calculate Maximum Heart Rate (Haskett formula) var maxHR = 220 – age; // 2. Calculate Heart Rate Reserve (HRR) var hrr = maxHR – restingHR; // 3. Calculate Target/Working Heart Rate var targetHR = (hrr * intensity) + restingHR; var roundedResult = Math.round(targetHR); document.getElementById("resultValue").innerHTML = roundedResult + " BPM"; document.getElementById("hrRange").innerHTML = "Estimated Max Heart Rate: " + maxHR + " BPM | Heart Rate Reserve: " + hrr + " BPM"; document.getElementById("hr-result").style.display = "block"; }

Understanding your working heart rate (also known as target heart rate) is the most effective way to ensure your cardiovascular workouts are both safe and effective. Whether you are training for a marathon or just trying to lose weight, monitoring your heart rate ensures you are exercising at the correct intensity.

What is Working Heart Rate?

Working heart rate refers to the frequency of heartbeats during physical activity. Unlike your resting heart rate, which measures your heart efficiency at rest, your working heart rate indicates how hard your cardiovascular system is working to supply oxygen to your muscles during movement.

The Karvonen Formula Explained

The calculator above uses the Karvonen Formula, which is widely considered more accurate than the standard "220 minus age" method because it takes your resting heart rate into account. This factor reflects your current fitness level.

The Formula:
Target Heart Rate = [(Max HR − Resting HR) × % Intensity] + Resting HR

Heart Rate Intensity Zones

Zone	Intensity	Benefit
Very Light	50-60%	Warm-up, recovery, and basic health.
Light (Fat Burn)	60-70%	Weight loss and building endurance.
Moderate (Aerobic)	70-80%	Improving cardiovascular fitness.
Hard (Anaerobic)	80-90%	Increasing speed and power.

Example Calculation

If you are a 40-year-old with a resting heart rate of 60 BPM and you want to exercise at 70% intensity:

• Max Heart Rate: 220 – 40 = 180 BPM
• Heart Rate Reserve (HRR): 180 – 60 = 120 BPM
• Working Heart Rate: (120 × 0.70) + 60 = 144 BPM

Frequently Asked Questions

How do I find my Resting Heart Rate?

The best time is in the morning before you get out of bed. Use two fingers to find your pulse on your wrist or neck and count the beats for 60 seconds.

Is 220 minus age always accurate?

No, it is a general estimate. It can vary by as much as 10-15 beats per minute depending on your genetics and fitness level. The Karvonen formula used above is significantly more personalized.

What if my heart rate is too high?

If your heart rate exceeds your target zone, slow down your pace or reduce resistance. If you feel dizzy, short of breath, or experience chest pain, stop exercising immediately and consult a physician.