Heart Rate Zone Calculator
Training in the right heart rate zone makes every workout more effective — whether your goal is burning fat, building aerobic base, or improving VO₂ max. This calculator uses your age and resting heart rate (optional) to determine your five training zones. For calorie context, pair your results with the TDEE Calculator.
The 5 Heart Rate Training Zones
| Zone | % of Max HR | Name | Primary Benefit |
|---|---|---|---|
| Zone 1 | 50–60% | Recovery | Active recovery, warm-up, cool-down |
| Zone 2 | 60–70% | Fat Burn / Base | Aerobic base, fat oxidation, endurance |
| Zone 3 | 70–80% | Aerobic / Cardio | Cardiovascular fitness, lactate threshold |
| Zone 4 | 80–90% | Threshold | High-intensity endurance, race pace |
| Zone 5 | 90–100% | Peak / VO₂ Max | Maximum speed and power (short bursts only) |
Zone 2 Training: The Most Underused Zone
Zone 2 — conversational-pace cardio at 60–70% of max HR — has gained significant attention in endurance sports science. Long zone 2 sessions (45–90 minutes) maximize mitochondrial density in slow-twitch muscle fibers, improving how efficiently your body uses fat as fuel. Elite endurance athletes typically spend 70–80% of their training time in Zone 2.
For most people, 3–4 hours of Zone 2 cardio per week produces measurable improvements in aerobic capacity within 8–12 weeks.
Choosing the Right Formula
220 − Age is the most widely used formula, though it can overestimate MHR in older adults and underestimate it in younger people.
Tanaka Formula (208 − 0.7 × Age) was derived from a meta-analysis of 351 studies and is generally considered more accurate across a broad age range — especially for adults over 40.
Karvonen Method factors in your resting heart rate to calculate your Heart Rate Reserve (MHR − RHR), then applies zone percentages to that reserve. This produces more personalized zones and is the recommended method if you know your resting HR. Measure your resting heart rate by counting beats for 60 seconds immediately upon waking, before getting out of bed.
How to Use Heart Rate Zones During Workouts
A chest strap heart rate monitor is the most accurate wearable option for zone training, as wrist-based optical HRM can lag during rapid changes. Monitors like the Polar H10 pair with most fitness apps and smartwatches.
- For fat loss: Prioritize Zone 2 sessions. Fat is the primary fuel source at this intensity.
- For cardiovascular fitness: Mix Zone 2 (base) with Zone 4 intervals (threshold).
- For performance: Add Zone 5 sprint intervals 1–2 times per week.
- For recovery: Keep sessions in Zone 1 — resist the urge to push harder.
Frequently Asked Questions
What is maximum heart rate? Maximum heart rate (MHR) is the highest number of times your heart can beat per minute during maximal exertion. It is primarily determined by age and genetics — training does not raise it significantly, but improved fitness means you can sustain higher percentages of MHR for longer.
How do I find my true maximum heart rate? A field test: after a thorough warm-up, run hard uphill for 2–3 minutes, then sprint for 30–60 seconds at maximum effort. Your peak reading during this effort is close to your true MHR. This test is not appropriate if you have cardiovascular conditions.
Why is my heart rate so high during easy runs? This is common in new runners and is often called "cardiac drift." As fitness improves your heart becomes stronger and more efficient, pumping more blood per beat — meaning it needs to beat fewer times to deliver the same oxygen. For beginners, perceived exertion is often a better guide than HR zones until a fitness base is established.
Is Zone 2 cardio the same as "fat-burning zone"? Yes — Zone 2 overlaps with what is commonly labeled the fat-burning zone. At this intensity, approximately 60–70% of energy comes from fat oxidation. However, total calorie burn is lower than at higher intensities, so the absolute amount of fat burned can be similar between zones depending on duration.
