Heart Rate Zones Calculator

What Is Resting Heart Rate (RHR)?

Your Resting Heart Rate is the number of times your heart beats per minute when you are completely at rest—ideally measured first thing in the morning before getting out of bed. A typical healthy adult RHR ranges from 60 to 100 bpm, but well-trained endurance athletes often have RHRs in the mid-40s to low-50s. A lower RHR generally indicates a more efficient heart function and better cardiovascular fitness.

Predicting Maximum Heart Rate

Because performing a true maximal exercise test requires specialized equipment and medical supervision, we often use field equations to estimate (predict) your Max HR. One common formula is the Tanaka equation:

Predicted Max HR = 208 − 0.7 × Age

For example, a 35-year-old would have an estimated Max HR of:

208 − 0.7 × 35 = 208 − 24.5 = 183.5 bpm (rounded to 184 bpm)

Note: Another classic formula you may hear is “220 − Age,” but Tanaka’s formula has been shown to be slightly more accurate across a wider age range in research studies.

What Is Heart Rate Reserve (HRR)?

Heart Rate Reserve is the difference between your Predicted Max HR and your Resting HR:

HRR = Predicted Max HR − Resting HR

HRR represents the total “reserve” your heart has for increasing intensity during exercise. The Karvonen method (also called the HRR method) then uses this reserve to define training zones. By working off HRR rather than a straight percentage of Max HR, you account for your unique resting baseline and your actual fitness level.

Understanding Heart Rate Zones

Training in specific Heart Rate Zones helps you target different physiological adaptations. We’ve divided HRR into five zones below:

• Zone 1 (Recovery / Very Light): 50–60 % of HRR (excellent for active recovery, very easy aerobic work). Example: Walking pace, easy cycling.
• Zone 2 (Endurance / Light): 60–70 % of HRR (improves basic aerobic endurance and fat-burning efficiency). Example: Comfortable jogging or easy cross-training.
• Zone 3 (Tempo / Moderate): 70–80 % of HRR (builds aerobic capacity, sustainable but somewhat challenging). Example: Steady run at a “conversation is possible but with effort” pace.
• Zone 4 (Threshold / Hard): 80–90 % of HRR (improves lactate threshold and high-end aerobic power). Example: Tempo intervals, moderate hill repeats.
• Zone 5 (VO₂max / Very Hard): 90–100 % of HRR (maximizes VO₂max and top-end performance). Example: Short all-out intervals (e.g., 30 sec sprints, or repeated 2–3 min efforts near max effort).

Why Train by Heart Rate Zone?

Structured Adaptations: By organizing workouts into distinct zones, you can target specific cardiovascular and metabolic adaptations:

• Zone 1 & 2 (Low Intensity): Builds capillary density, mitochondrial function, and fat-oxidation efficiency—foundational for endurance.
• Zone 3 (Moderate): Increases aerobic capacity by pushing you slightly above comfortable pace, bridging easy and hard work.
• Zone 4 (Threshold): Raises your lactate threshold, allowing you to sustain higher intensities before fatigue.
• Zone 5 (VO₂max): Maximizes oxygen-uptake capacity and neuromuscular recruitment for peak performance.

Autoregulation & Recovery: Monitoring your heart rate ensures you’re truly in the intended zone. If your HR is higher than expected for a “Zone 2” day, it may signal fatigue or inadequate recovery—so you can adjust accordingly.

Tips for Using This Calculator

• Measure Resting HR Accurately: Take your pulse first thing in the morning, before sitting up, for 60 seconds. Use a heart-rate monitor strap or watch if possible—wrist monitors can be slightly less accurate at rest.
• Age-Based Max HR Is an Estimate: If you’ve recently done a maximal treadmill or bike test under supervision, use your measured Max HR instead of the formula. Otherwise, age‐based predictions (like Tanaka’s) are usually within 5–10 bpm of your true max.
• Use a Reliable HR Monitor: Chest straps are more accurate at higher intensities. Wrist or optical sensors can lag when you change effort quickly.
• Re-Test Periodically: As your fitness improves, your resting HR may drop. Re‐enter your updated Resting HR and Age to recalculate HR zones every 3–6 months.
• Integrate Zones into Workout Plans: • Base Phase (High Volume, Low Intensity): 80–90 % of weekly minutes in Zones 1–2. • Build Phase (Moderate/Threshold): 10–15 % in Zone 3–4. • Intensity Phase (VO₂max/Sprints): 5–10 % in Zone 5.

By consistently training in the correct zones, you’ll maximize your aerobic efficiency, delay fatigue, and ultimately perform at a higher level—whether you’re a recreational runner, a cyclist, a grappler, or simply someone who wants to improve their cardiovascular health.