Key Takeaways
- "Zone 2" has no single published definition. At a maximum of 180 bpm, the bands I found put the top of zone 2 anywhere from 126 to 148 bpm[1][2][4][5].
- The default here is a 2025 expert panel's description: about 70 to 80% of maximum heart rate, or 80 to 90% of the heart rate at your first lactate threshold[1]. It is a consensus of 14 cycling-focused men, not a trial.
- A fixed percent of maximum misplaces some people. In 50 cyclists, the first threshold averaged 81.4% of maximum with a standard deviation of 3.9 points, and the authors advise measuring it[2].
- Your maximum is usually an estimate too. Age equations carry a standard error of about 7 to 11 bpm[18], so a test result or the talk test is a better check than any number from age alone.
- This tool gives heart rate only. I found no source I could use to turn a zone 2 heart rate into a pace or a power, so it does not guess.
What Zone 2 Means
A word that is used loosely, and that experts recently tried to pin down.
In the five-zone model most watches use, zone 2 is the easy, steady step above recovery. Endurance scientists mean something tighter by it. In 2025, 14 sport scientists and coaches from 8 countries wrote down what they mean[1].
They put zone 2 just below the first lactate or ventilatory threshold (LT1 or VT1), where blood lactate holds steady at about 1 to 2 mmol/L. Heart rate there is about 70 to 80% of maximum, or 80 to 90% of the heart rate at LT1[1].
Effort is low, about 10 on the 6 to 20 Borg scale[1].
That paper is a consensus statement from men with a cycling focus, not a trial. I use its band as the default, and I show the other published bands beside it so you can see how far they differ.
Whose Zone 2? Four Published Answers
Same person, same maximum of 180 bpm, and the top of the zone moves by 22 beats.
| Source | % of max | bpm at 180 |
|---|---|---|
| Expert panel, 2025[1] | 70 to 80 | 126 to 144 |
| Seiler's intensity table, level 2[1] | 67 to 82 | 121 to 148 |
| Norwegian Olympic Federation range[2] | 72 to 82 | 130 to 148 |
| Garmin and Polar default[4][5] | 60 to 70 | 108 to 126 |
Each band applied to a maximum of 180 bpm (age 40 on the 220 minus age rule)
The panel anchors zone 2 to LT1 and then describes it as a percent of maximum[1]. Seiler's five-level table, reprinted in that paper, gives a wider band at level 2, with a Borg rating of 9 to 12[1]. Meixner and colleagues describe 72 to 82% as the Norwegian Olympic Federation range[2].
Garmin and Polar both set zone 2 at 60 to 70% of maximum heart rate, a plain split of the range, and Garmin's default maximum is 220 minus age[4][5]. Peter Attia defines zone 2 by lactate instead, as the highest effort that keeps it under about 2 mmol/L[17].
Polar's own guide says the first threshold can fall anywhere from 60 to 85% of true maximum, depending on the person[6]. A fixed band cannot follow a range that wide, which is why the lab data below matters.
How the Calculator Works
Percent of maximum heart rate, with the percent set by the definition you pick.
The low end is your maximum times the lower percent, and the high end is your maximum times the upper percent. Halves round up, which is how the American Heart Association chart rounds, so you can check any figure by hand[27].
Worked example: age 40
Heart rate reserve does not set the zone here. I found no source that ties a percent of reserve to zone 2, so a resting rate only changes the reserve figure shown in the results. It is arithmetic, not a published zone.
The maximum comes from the same six equations as the Target Heart Rate Zones calculator, or from a maximum you measured. The choice matters, as the table shows for age 50.
| Equation | Max | Zone 2 bpm |
|---|---|---|
| 220 − age | 170 | 119 to 136 |
| Tanaka (2001) | 173 | 121 to 138 |
| Gellish (2007) | 172 | 120 to 138 |
| HUNT (2013) | 179 | 125 to 143 |
| Gulati (2010) | 162 | 113 to 130 |
| Inbar (1994) | 172 | 120 to 138 |
Expert panel band (70 to 80%) at age 50 with each maximum equation
Gulati was built on women and Inbar on men, so use them only if they fit you[22][23]. Tanaka and HUNT found no difference between men and women[19][21].
Zone 2 Heart Rate by Age
The expert panel band and the Garmin and Polar band, on the 220 minus age rule.
| Age | Max | Panel, 70 to 80% | Watch, 60 to 70% | 180 − age |
|---|---|---|---|---|
| 20 | 200 | 140 to 160 | 120 to 140 | 160 |
| 30 | 190 | 133 to 152 | 114 to 133 | 150 |
| 40 | 180 | 126 to 144 | 108 to 126 | 140 |
| 50 | 170 | 119 to 136 | 102 to 119 | 130 |
| 60 | 160 | 112 to 128 | 96 to 112 | 120 |
| 70 | 150 | 105 to 120 | 90 to 105 | 110 |
Maximum is 220 minus age. The last column is 180 minus age, the Maffetone starting figure.
Two people of the same age can sit well away from these rows. The table is a starting point, and the calculator above lets you swap the maximum for a measured one.
Setting Zone 2 From a Test
Closer to the panel's definition, because it starts from your own threshold.
Meixner and colleagues advise measuring VT1 or Fat Max instead of using a fixed percent[2]. If you have a lactate or gas-exchange result, enter the heart rate at LT1 or VT1, and the tool applies the panel's 80 to 90% and shows LT1 itself as the ceiling[1][12].
Friel's current guide, revised in September 2025, says LT1 sits at 2 mmol/L and "establishes the top end of your zone 2"[12]. So the LT1 heart rate works as a ceiling, and the panel's 80 to 90% of it is the heart rate they expect for a steady session[1].
Worked example: LT1 at 146 bpm
You may still see Friel's older zone table, which puts zone 2 at 85 to 89% of lactate threshold heart rate for running and 81 to 89% for cycling[10]. It dates from 2009 and comes from a solo 30-minute test[11].
His revised guide says he reworked the zones and no longer gives separate running and cycling ranges[12]. I could not read the percentages in the new table, so the calculator uses neither version.
The talk test is a free cross-check. In one study of healthy young adults, the last stage where people could still speak comfortably tracked their ventilatory threshold[13]. A review in heart and lung patients supports its validity but notes there is no well-defined protocol[15].
The Maffetone 180 Formula
A different idea, reached by a rule and not by lactate testing.
Phil Maffetone's formula starts at 180 minus your age, then adjusts for health and training history[7][8]. The result is the top of a range whose low end is 10 beats below. For athletes 16 and under, he has used 165 and says the formula does not apply.
| Category | Who it fits | Change |
|---|---|---|
| A | Major illness, surgery, rehab, regular medication or chronic overtraining (subtract 10) | -10 |
| B | Injured, not improving, frequent colds, allergies or asthma, overfat, or new or returning to training (subtract 5) | -5 |
| C | Training at least four times a week for up to two years with none of the above (no change) | 0 |
| D | Training more than two years, still improving, no injury (add 5) | +5 |
Maffetone's adjustment by category
Worked example: age 40, category B
Maffetone writes that the formula is not a replacement for laboratory testing, although he says it usually corresponds well with lab measures[8]. The 2015 study of the method followed 5 km race times and injury rates in runners[9]. I did not find an independent study that checked it against a measured threshold.
How Far to Trust Any Zone 2 Number
Four sources of error stack on top of each other.
First, the definition. The first threshold in 50 experienced cyclists (30 men and 20 women) averaged 81.4% of maximum heart rate, with a standard deviation of 3.9 points[2]. At a maximum of 180, five points is 9 beats.
| Marker | % of max | Heart rate |
|---|---|---|
| VT1, the top edge of zone 2[2] | 81.4 ± 3.9 | 146 ± 11 bpm |
| Fat Max, where fat use peaks[2] | 72.3 ± 5.7 | 130 ± 12 bpm |
Lab means from 50 cyclists, with a mean maximum of 179 bpm (plus or minus 10)
Second, the maximum. Age equations carry a standard error of about 7 to 11 bpm[18], and Mayo Clinic says individual maximums can differ by as much as 15 to 20[25].
Third, the sport. In 16 healthy volunteers, heart rate at the ventilatory threshold was 89% of peak on a treadmill and 82% on a bike[14]. So one threshold can sit at a different percent of peak depending on the activity.
Fourth, who was studied. The panel was 14 men[1]. In 165 recreational runners (64 women), the first threshold came at a higher relative heart rate in women than in men[28].
Fixed heart rate anchors built from that group's own sex-specific means still missed LT1 by 4.9 to 7.4 bpm on average[28]. A percent taken from men may sit too low for women.
Zone 2 and the Fat Burning Zone
Related, but not the same thing.
In the cyclists above, Fat Max averaged 72.3% of maximum heart rate and VT1 averaged 81.4%. The authors call the two markers strongly aligned, and say Fat Max and VT1 may overlap in some riders. Even so, Fat Max was generally about 25% lower in power, which they read as two distinct intensity domains[2].
So on average the peak of fat use sat below the top of zone 2 in this group, though the two can sit close together for a given person. If you came here for fat loss, the Fat Burning Zone Calculator covers what the research says about that range.
How Much Zone 2 Training
Where the numbers come from, and which ones are only recommendations.
The expert panel's preferred method is long continuous rides, ideally over two hours. They also describe variable and interval sessions, and say to watch both heart rate and effort because heart rate drifts upward over time[1]. That advice was written about cycling.
Attia recommends about 2 hours a week to start, and ideally 3 to 4[16]. He does not cite a trial for those numbers on the pages I read, so treat them as his recommendation.
Seiler's 2010 review describes a pattern of about 80% of sessions at low intensity and about 20% at high intensity[3]. It counts sessions, not minutes, and it does not map to a heart rate percent, so this tool does not turn it into one.
Limits and What Is Left Out
What the tool does not do, so you do not read more into it than is there.
It gives heart rate only. I found no source I could rely on for a zone 2 pace or power from age or heart rate, so there is none here. For power-based zones, see the Cycling Power Training Zones calculator.
It does not adjust for fitness level, heat, altitude, sleep or caffeine. It also does not tell you whether your zone 2 is the right dose, because no source I read gives a dose by heart rate.
For a full set of heart rate zones, use the Target Heart Rate Zones calculator. For a session score once you have trained, try the TSS calculator.
Frequently Asked Questions
Sources & References
- What Is "Zone 2 Training"?: Experts' Viewpoint on Definition, Training Methods, and Expected Adaptations. Sitko S, et al. (14 authors). International Journal of Sports Physiology and Performance 20(11):1614-1617 (2025)
- Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries. Meixner B, Filipas L, Holmberg H-C, Sperlich B. Translational Sports Medicine 2025:2008291 (2025)
- What is best practice for training intensity and duration distribution in endurance athletes?. Seiler S. International Journal of Sports Physiology and Performance 5(3):276-291 (2010)
- How you can train by heart rate zones using Garmin. Garmin. Garmin blog
- Heart Rate Zones. Polar. Polar Global guide
- How to Set Your Training Zones in Polar. Polar. Polar Global guide
- Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application. Maffetone PB, Laursen PB. Frontiers in Physiology 11:296 (2020)
- MAF 180: Personalizing Exercise Heart Rate (2019 formula). Maffetone P. philmaffetone.com
- The Development and Initial Assessment of a Novel Heart Rate Training Formula. Høeg TB, Maffetone PB. Wilderness & Environmental Medicine (2015)
- Joe Friel's Quick Guide to Setting Training Zones. Friel J. TrainingPeaks Learn (reprints Friel's 2009 zone table; page updated July 2026)
- Determining your LTHR. Friel J. joefrieltraining.com (blog post, April 2011)
- A Quick Guide to Setting Zones. Friel J. joefrieltraining.com (revised September 2025)
- The Talk Test as a Marker of Exercise Training Intensity. Foster C, Porcari JP, Anderson J, Paulson M, Smaczny D, Webber H, Doberstein ST, Udermann B. Journal of Cardiopulmonary Rehabilitation and Prevention (2008)
- Consistency of the talk test for exercise prescription. Persinger R, Foster C, Gibson M, Fater DC, Porcari JP. Medicine & Science in Sports & Exercise (2004)
- Application and Measurement Properties of the Talk Test in Cardiopulmonary Patients: A Systematic Review. Vieira AM, Martins EM, Althoff A, Rech DA, Ribeiro GS, Matte DL, Karsten M. Reviews in Cardiovascular Medicine 23(7):225 (2022)
- Peter Attia on Zone 2 and Zone 5 Training (from Ask Me Anything #12). Attia P. peterattiamd.com (2022)
- AMA #19: Deep dive on Zone 2 training (show notes). Attia P. peterattiamd.com (2021)
- The surprising history of the "HRmax=220-age" equation. Robergs RA, Landwehr R. Journal of Exercise Physiology online (2002)
- Age-predicted maximal heart rate revisited. Tanaka H, Monahan KD, Seals DR. Journal of the American College of Cardiology (2001)
- Longitudinal modeling of the relationship between age and maximal heart rate. Gellish RL, Goslin BR, Olson RE, McDonald A, Russi GD, Moudgil VK. Medicine & Science in Sports & Exercise (2007)
- Age-predicted maximal heart rate in healthy subjects: The HUNT fitness study. Nes BM, Janszky I, Wisløff U, Støylen A, Karlsen T. Scandinavian Journal of Medicine & Science in Sports (2013)
- Heart rate response to exercise stress testing in asymptomatic women: the St. James Women Take Heart Project. Gulati M, Shaw LJ, Thisted RA, Black HR, Bairey Merz CN, Arnsdorf MF. Circulation (2010)
- Normal cardiopulmonary responses during incremental exercise in 20- to 70-yr-old men. Inbar O, Oren A, Scheinowitz M, Rotstein A, Dlin R, Casaburi R. Medicine & Science in Sports & Exercise (the abstract gives the slope only; the intercept is confirmed through Robergs and Landwehr) (1994)
- Accuracy of Commonly Used Age-Predicted Maximal Heart Rate Equations. Shookster D, Lindsey B, Cortes N, Martin JR. International Journal of Exercise Science (2020)
- Exercise intensity: How to measure it. Mayo Clinic
- Beta blockers: How do they affect exercise?. Mayo Clinic
- Target Heart Rates Chart (reviewed August 2024). American Heart Association (2024)
- The accuracy of fixed intensity anchors to estimate lactate thresholds in recreational runners. Nuuttila O-P, Kaikkonen P, Sievänen H, Vasankari T, Kyröläinen H. European Journal of Applied Physiology 125(8):2161-2171 (2025)
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Disclaimer: This calculator is for informational and personal journaling purposes only. It logs measurements and compares them to published reference values. It is not health, medical, or nutrition advice.