Heart Rate Zone Calculator
Max HR estimation formula
Enables Karvonen method
Overrides formula estimate
Enables Friel 7-zone method
Upload a FIT file from a hard workout or race to auto-detect your max HR
.fit files from Garmin, Wahoo, COROS, Strava
I'm Jason, a software engineer and runner based in New York City. I built this tool to support my own training and I hope it helps yours too! If you have feedback or ideas, feel free to message me on Instagram or LinkedIn.
What Are Heart Rate Zones?
Heart rate zones divide your training intensity into ranges based on your maximum heart rate. The standard 5-zone model goes from easy recovery (Zone 1) through aerobic base building (Zone 2), tempo (Zone 3), threshold (Zone 4), and all-out effort (Zone 5). Training in different zones targets different physiological adaptations — Zone 2 builds your aerobic engine, while Zone 4–5 improves speed and VO2max.
Norwegian researcher Stephen Seiler studied elite endurance athletes across sports and found they consistently spend roughly 80% of their training time at low intensity (Zones 1–2) and 20% at high intensity (Zones 4–5), with relatively little time in the moderate Zone 3. This polarized training model has been widely adopted. Matt Fitzgerald popularized this approach for recreational runners in his book 80/20 Running, arguing that most runners train too hard on easy days and too easy on hard days.
How to Find Your Max Heart Rate
The most widely cited formula is 220 minus your age, introduced by Fox in 1971. However, this formula has a standard deviation of ±10–12 bpm, meaning it can be off by a full zone for many people. The Tanaka formula (208 − 0.7 × age), based on a 2001 meta-analysis of 351 studies and 18,712 subjects published in the Journal of the American College of Cardiology, is more accurate, especially for adults over 40.
The best approach is to measure your actual max HR. A simple field test: after a thorough warmup, run 3 × 3-minute hard hill repeats with a jog recovery between each. Push to maximum effort on the last one. Your peak heart rate from that effort is close to your true max. Alternatively, upload a FIT file from your hardest recent race — the max HR recorded during an all-out effort is typically a reliable number.
Which Method Should I Use?
This calculator supports four different zone calculation methods. The best one depends on what data you have:
| What You Know | Best Method | Why |
|---|---|---|
| Only your age | Max HR % | Simplest starting point, requires no testing |
| Age + resting HR | Karvonen (HRR) | Accounts for your fitness level via resting HR. ACSM-recommended |
| Lactate threshold HR | Friel / LTHR | Most accurate non-lab method. Joe Friel's system, used by TrainingPeaks |
| Want a simple ceiling | MAF 180 | Phil Maffetone's method, popular in ultra/triathlon |
| A recent hard-effort FIT file | Upload it | Your actual max HR beats any formula |
The Karvonen method, first described by Finnish scientist Martti Karvonen in 1957, uses heart rate reserve (max HR minus resting HR) as the working range. Because it incorporates your resting heart rate, it produces more personalized zones — a fit runner with a resting HR of 48 will get different zones than a beginner with a resting HR of 72. The Friel method, developed by coach Joe Friel and detailed in his Training Bible series, anchors all zones to your lactate threshold heart rate — the intensity at which lactate begins to accumulate faster than your body clears it. To find your LTHR, Friel recommends a simple field test: run solo at maximum sustainable effort for 30 minutes, and your average HR for the last 20 minutes approximates your LTHR.
Zone 2 Training: Why Everyone Is Talking About It
Zone 2 has become the most talked-about training zone in endurance sports and beyond. Dr. Peter Attia, physician and longevity researcher, advocates zone 2 training as one of the most impactful things you can do for metabolic health and longevity — not just athletic performance. At this intensity, your body primarily burns fat, builds mitochondrial density, and improves the aerobic base that supports everything from daily energy to racing.
The challenge is that zone 2 feels too easy for most people. Without a heart rate target, runners tend to drift into zone 3 — the "no man's land" that is too hard for aerobic development but too easy for threshold gains. This is exactly why having a calculated ceiling helps: it gives you a number to stay under. David Roche, coach of Some Work, All Play (SWAP) and two-time Leadville 100 champion, recommends that beginners keep 70–80% of weekly volume in Zones 1–2, using heart rate rather than pace to regulate easy efforts.
For zone 2 training on a treadmill, try our treadmill elevation gain calculator to track vertical gain during incline walks. To convert your zone 2 heart rate into a target pace, use our running pace calculator.
Zone 2 Heart Rate by Age
Quick reference for zone 2 heart rate ranges by age, using the Tanaka formula (208 − 0.7 × age) for max HR estimation. The Karvonen column assumes a resting heart rate of 60 bpm — if yours is lower, your zone 2 range will be slightly higher.
| Age | Max HR (Tanaka) | Zone 2 (Max HR %) | Zone 2 (Karvonen, RHR=60) |
|---|---|---|---|
| 20 | 194 | 116–136 | 140–154 |
| 25 | 191 | 115–134 | 139–152 |
| 30 | 187 | 112–131 | 136–149 |
| 35 | 184 | 110–129 | 134–147 |
| 40 | 180 | 108–126 | 132–144 |
| 45 | 177 | 106–124 | 130–142 |
| 50 | 173 | 104–121 | 128–139 |
| 55 | 170 | 102–119 | 126–137 |
| 60 | 166 | 100–116 | 124–134 |
| 65 | 163 | 98–114 | 122–132 |
| 70 | 159 | 95–111 | 119–129 |
Common Questions (FAQ)
What are the 5 heart rate zones?
The standard 5-zone model divides training intensity based on percentage of max heart rate. Zone 1 (50–60%) is recovery. Zone 2 (60–70%) is aerobic base building — conversational pace. Zone 3 (70–80%) is tempo effort. Zone 4 (80–90%) is lactate threshold. Zone 5 (90–100%) is VO2max — maximum effort for intervals and sprints. Zones help you train at the right intensity for your goals rather than guessing.
How do I calculate my heart rate zones?
Start with your max HR. If you don't know it, the Tanaka formula (208 − 0.7 × age) is the most accurate age-based estimate, supported by a 2001 meta-analysis of 18,712 subjects. Multiply by the zone percentages (e.g., 60–70% for zone 2). For more accurate zones, use the Karvonen method which factors in your resting heart rate, or the LTHR method if you know your lactate threshold from a field test.
What is zone 2 heart rate?
Zone 2 is typically 60–70% of your max heart rate. It feels like a conversational pace — you can speak in full sentences without gasping. This is the intensity recommended for the majority of endurance training. Peter Attia advocates zone 2 as the foundation of metabolic health and longevity, describing it as the highest intensity at which you can keep blood lactate below 2 mmol/L.
What is a good zone 2 heart rate by age?
Using the Tanaka formula (208 − 0.7 × age), zone 2 at 60–70% of max HR looks like: age 30 ≈ 112–131 bpm, age 40 ≈ 108–126 bpm, age 50 ≈ 104–121 bpm, age 60 ≈ 100–116 bpm. With the Karvonen method (assuming resting HR of 60), these ranges shift higher. See the Zone 2 by Age table above for a complete reference.
What is the Karvonen formula?
The Karvonen formula calculates heart rate zones using heart rate reserve (HRR = max HR − resting HR). The target is: Resting HR + (HRR × intensity %). Originally described by Finnish scientist Martti Karvonen in 1957, it is recommended by the American College of Sports Medicine because HRR percentages correlate more closely with VO2max percentages than simple max HR percentages. This means a fit person with a low resting HR gets appropriately different zones than a beginner.
What is the difference between Max HR zones and Karvonen zones?
Max HR zones use simple percentages of your max heart rate. Karvonen zones use heart rate reserve, which subtracts your resting heart rate first, then adds it back. Karvonen zones are always higher because they account for your resting HR baseline. The fitter you are (lower resting HR), the bigger the gap between the two methods. For someone with max HR 185 and resting HR 50, zone 2 is 111–130 bpm (Max HR %) vs 131–145 bpm (Karvonen) — a significant difference.
What is lactate threshold heart rate (LTHR)?
LTHR is the heart rate at which lactate begins to accumulate faster than your body can clear it — the boundary between sustainable and unsustainable effort. Joe Friel, author of The Triathlete's Training Bible, popularized a simple field test: run solo at maximum sustainable effort for 30 minutes, and your average HR for the last 20 minutes approximates your LTHR. His 7-zone system uses LTHR as the anchor point rather than max HR, producing more physiologically meaningful zones.
What is the MAF 180 formula?
The MAF (Maximum Aerobic Function) formula is 180 minus your age, giving a single aerobic ceiling heart rate. Developed by Phil Maffetone, who coached triathlon legend Mark Allen to six Ironman World Championship titles, it is popular in ultra and triathlon communities. Unlike zone-based systems, MAF gives one number — stay below it for all aerobic training. Adjustments of ±5–10 bpm are made based on training history and health.
How accurate is 220 minus age for max heart rate?
The 220 − age formula (Fox, 1971) is widely cited but has a standard deviation of about ±10–12 bpm. A 2001 meta-analysis by Tanaka et al. (351 studies, 18,712 subjects) found that 208 − 0.7 × age is more accurate, especially for older adults. Even Tanaka has a standard error of ~10 bpm. Both are estimates — a field test (3 × 3-minute hard hill repeats) or uploading a FIT file from a recent all-out race gives a more reliable number.
Should I train by heart rate or pace?
Heart rate reflects internal effort; pace reflects external output. On hot days, hills, or when fatigued, the same pace requires a higher heart rate. Heart rate zones are especially useful for easy and recovery runs to prevent going too hard. Many coaches, including David Roche of SWAP Running, recommend using heart rate for easy days and pace for workouts. The best approach is using both together — heart rate as a ceiling on easy days, pace as a floor on hard days. Use our running pace calculator to pair your zone targets with specific paces.