Heart Rate Zone Calculator

Age

Resting heart rate (optional)

Formula

Estimated Max Heart Rate

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Resting HR used

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Understanding heart rate training zones

Training in specific heart rate zones allows you to target different physiological adaptations — from improving fat metabolism to building cardiovascular endurance to developing peak speed and power. Most endurance training programs use a 5-zone model.

The 5 zones explained

Zone 1 – Recovery (50–60%): Very light effort. Active recovery, warm-ups, cool-downs. Promotes blood flow and muscle repair without adding fatigue.
Zone 2 – Aerobic base (60–70%): The "fat burning zone." Conversational pace. Builds aerobic base and fat-oxidation efficiency. Most endurance training should happen here.
Zone 3 – Aerobic (70–80%): Moderate effort. Improves aerobic capacity and muscular endurance. Sustainable for 30–60 minutes.
Zone 4 – Threshold (80–90%): Hard effort. Raises lactate threshold — your ability to sustain high intensity. Interval training and tempo runs live here.
Zone 5 – VO2 Max (90–100%): Maximum effort. Short bursts only. Develops VO2 max and neuromuscular power. Unsustainable for more than a few minutes.

Karvonen vs. % of Max HR

The Karvonen method uses Heart Rate Reserve (HRR = Max HR − Resting HR) to calculate zones. Because it accounts for your resting heart rate, it's more individualised and generally considered more accurate, especially for fit individuals with a low resting HR.

The % of Max HR method is simpler — it just takes percentages of your maximum heart rate directly. It's less personalised but still useful if you don't know your resting HR.

How to measure your resting heart rate

Measure first thing in the morning before getting out of bed. Count your pulse for 60 seconds (or 30 seconds × 2). A typical resting HR is 60–80 bpm; well-trained athletes often see 40–55 bpm. Wearables like Garmin or Whoop can track this automatically overnight.

How to find your true maximum heart rate

The 220 − age formula is a useful estimate, but actual maximum heart rate varies significantly between individuals — often by ±10–20 bpm. If you use a heart rate monitor consistently, the highest reading you have ever seen during maximal effort (a sprint finish, a hard hill) is a better estimate than any formula. Lab-based VO2 max testing produces the most accurate result.

Zone 2: why it gets most of the attention

Zone 2 has attracted significant attention from longevity researchers and endurance coaches for good reason. It's the zone that drives mitochondrial development — increasing the number and efficiency of the cellular engines that produce aerobic energy. More mitochondria means better fat oxidation, more aerobic power, and better endurance at any intensity. Most endurance athletes spend 80% of their training volume in Zone 2.

Zone 4: the threshold zone

Zone 4 — the lactate threshold zone — is where meaningful improvements in sustained hard effort happen. Your lactate threshold is the highest intensity at which lactate production and clearance are in balance. Training at and just above this threshold raises the ceiling of what you can sustain, improving race performance and high-intensity fitness. Tempo runs, sweet spot intervals, and threshold intervals all target Zone 4.

Zone 5: when to use it

Zone 5 (90–100% max HR) is reserved for short, maximal bursts — sprints, intervals of 30 seconds to 2–3 minutes. These sessions develop VO2 max, neuromuscular power, and anaerobic capacity. Zone 5 cannot be sustained for more than a few minutes and requires full recovery between efforts. Two Zone 5 sessions per week is typically the maximum for trained athletes; once weekly is more appropriate for recreational fitness.

Practical training balance by goal

Goal	Zone 1–2	Zone 3–4	Zone 5
General health / longevity	70–80%	15–20%	5%
Fat loss	60–70%	20–25%	10%
Endurance performance	80%	15%	5%
General fitness (mixed)	50–60%	30–35%	10%

Frequently asked questions

How do I find my max heart rate?

The most common formula is 220 minus your age. This is an estimate — actual maximum heart rate varies by ±10–20 bpm between individuals. The most accurate method is a maximal effort test (a full sprint to exhaustion), but this should only be done by those in good cardiovascular health.

What heart rate zone burns the most fat?

Zone 2 (60–70% of max HR) has the highest proportion of fat burned per calorie, which is why it's called the "fat burning zone." However, higher-intensity zones burn more total calories per minute — so total fat loss depends on total calorie expenditure, not just the percentage from fat.

How do I measure heart rate during exercise?

A chest strap monitor is most accurate. Optical wrist-based monitors (like those in smartwatches) are convenient and reasonably accurate for steady-state cardio but less reliable during high-intensity intervals due to wrist movement. For Zone 2 training where precision matters, a chest strap is worth using.

Should most of my training be in Zone 2?

For endurance athletes, yes — 80% of training volume in Zone 2 with 20% in higher zones is a well-supported approach. For general fitness, a mix of Zone 2 (aerobic base), Zone 3–4 (cardio fitness), and occasional Zone 5 (peak effort) produces well-rounded cardiovascular fitness.

What is Zone 3 training good for?

Zone 3 (70–80% max HR) is the "aerobic" or "tempo" zone — it improves aerobic capacity and muscular endurance and is sustainable for 30–60 minutes. However, it accumulates more fatigue than Zone 2 without providing the clear adaptations of Zone 4 — which is why endurance coaches caution against spending too much time in Zone 3 ("grey zone" training).

How do I use heart rate zones for weight loss?

Zone 2 burns the highest proportion of fat per calorie and is sustainable for long sessions — making it effective for total fat burned per workout. Zone 4–5 intervals burn more total calories per minute but cannot be sustained as long. A practical approach: 3–4 Zone 2 sessions per week plus 1–2 higher-intensity sessions, combined with a moderate calorie deficit.

Does resting heart rate affect my zones?

Yes — the Karvonen method accounts for resting heart rate because your heart is already beating at that rate at rest. Someone with a resting HR of 45 bpm has a much larger working range above rest than someone at 75 bpm. Using the Karvonen method gives more personalised zones, especially for fit individuals with a low resting HR.

Not medical advice. Heart rate zone calculations are estimates based on population averages. If you have any cardiovascular condition or are new to exercise, consult a doctor before beginning a training program. Stop exercise immediately if you experience chest pain, dizziness, or shortness of breath.