Cardio
Zone 2 Heart Rate Calculator
Calculate your Zone 2 heart rate range with Maffetone, Karvonen, % Max HR, and lactate threshold methods side by side.
Result
The 3 methods span 36 bpm, from 114 to 150 bpm. Start at the bottom of your range and use the talk test: full sentences should stay easy. Add a resting heart rate to include Karvonen.
Zone 2 by method
Highlighted: the method these inputs support best.
| Method | Zone 2 | Rests on |
|---|---|---|
| Maffetone (MAF 180) | 140–150 bpm | No max HR: 180 − age, adjusted (MAF 150 bpm) |
| % of Max HR (estimated) | 114–133 bpm | Max 190 bpm (220 − age) |
| Karvonen (Heart Rate Reserve) | Needs resting HR | Resting heart rate and max |
| Lactate Threshold Estimate | 125–141 bpm | 87.5% of max 190 bpm (220 − age) |
Formula from Karvonen (1957) and Seiler training-intensity distribution (2010), checked against the source on May 25, 2026.
How to use it
- Enter your age as the minimum required input. Optionally add your resting heart rate (measured first thing in the morning before getting out of bed, averaged over 3 consecutive days) and your tested maximum heart rate if you have one from a graded exercise test or a recent all-out effort. Without a measured max, pick the age formula: 220 − age (the default, as on the Heart Rate Zone Calculator) or Tanaka 208 − 0.7 × age. Then pick your Maffetone adjustment: −10 if recovering from major illness or on regular medication, −5 if injured, regressing, often ill or returning to training, 0 if training consistently, +5 after two or more years of progress without those problems. The calculator compares four methods: the Maffetone MAF 180 formula, the percentage-of-max-HR method (60-70% of max HR), the Karvonen heart rate reserve method, and a lactate-threshold-derived estimate.
- Review all four Zone 2 ranges side by side in the comparison table. The Karvonen method, developed by Dr. Martti Karvonen in 1957, accounts for heart rate reserve (HRR = max HR - resting HR) and is considered the most individualized formula because it adjusts for your cardiovascular fitness level. The formula calculates Zone 2 as: target HR = ((max HR - resting HR) x intensity%) + resting HR, using 60-70% intensity for Zone 2. At the same max HR, a lower resting heart rate gives a slightly lower band: each 10 bpm drop in resting HR lowers Zone 2 by 3-4 bpm (for a max of 190, resting 50 gives 134-148 bpm and resting 75 gives 144-156 bpm). The percentage-of-max-HR method simply uses 60-70% of max HR (measured, or 220 - age, or Tanaka 208 - 0.7 x age) and does not account for resting HR, making it less precise but simpler.
- Understand why the methods produce different ranges and which to trust. The calculator highlights Karvonen when you give a resting heart rate, % of max when you give a measured max without one, and otherwise Maffetone, which was designed for aerobic base training and needs only your age. Note that the age-only methods disagree: for a 30-year-old, Maffetone gives 140-150 bpm while 60-70% of 220 − age gives 114-133 bpm. When in doubt, start at the lower range; drifting above the first lactate threshold turns an easy session into a moderate one. Elite endurance athletes do most of their training at or below the first ventilatory threshold (Seiler and Kjerland, 2006).
- Apply your Zone 2 range to structured training. A common coaching prescription is 3-4 sessions per week of 45-60 minutes each, which also covers the WHO guideline of 150-300 minutes of moderate activity a week. San Millán and Brooks (2018) use the intensity where lactate stays low and fat oxidation peaks as a marker of metabolic flexibility; easy endurance volume is what raises that intensity over time. Validate your Zone 2 during exercise using the 'talk test': you should be able to speak in full, continuous sentences without needing to pause for breath. If you can only manage short phrases, you have drifted above Zone 2.
- Re-run this calculator every 2-3 months, or when your resting heart rate or a newly measured max changes. Consistent aerobic training often lowers resting heart rate, which lowers the Karvonen band by 3-4 bpm per 10 bpm drop. The surer sign of progress is pace or power at the same Zone 2 heart rate rising over those months. If your resting heart rate has not changed after 3 months of Zone 2 training, verify that you are actually staying within the zone during sessions using a heart rate monitor, as most recreational athletes train too hard without realizing it.
Questions people usually ask
What is Zone 2 heart rate training and why does it matter?
Zone 2 is the easy aerobic intensity just below the first lactate threshold (close to the first ventilatory threshold), where blood lactate stays near resting levels and fat oxidation is near its peak. San Millán and Brooks (2018) measured lactate and fat oxidation in professional cyclists, moderately active people and people with metabolic syndrome and use this intensity as a marker of metabolic flexibility. Endurance athletes do most of their training at or below it (Seiler and Kjerland, 2006). At this intensity you should be able to speak in full sentences without pausing for breath.
Which Zone 2 calculation method is most accurate?
No formula is perfectly accurate without laboratory lactate testing or a ventilatory threshold test. The Karvonen method (heart rate reserve) is the most individualized because it accounts for both max HR and resting HR, adjusting the zone for your cardiovascular fitness level. If you only know your age, the Maffetone MAF 180 formula (180 - age, with adjustments for training status and health conditions) is a reliable conservative starting point developed by Dr. Phil Maffetone and used by endurance coaches worldwide since the 1980s. The percentage-of-max-HR method (60-70%) is the simplest but least personalized. For serious athletes, a laboratory lactate test (Zone 2 sits at or just under about 2 mmol/L) is the closest to a direct measurement.
Why do the four methods give different Zone 2 ranges?
Each method uses different physiological assumptions and inputs. The Maffetone MAF 180 formula uses only age and produces a single ceiling number, making it conservative. The percentage-of-max-HR method applies 60-70% to an estimated max HR (220-age or Tanaka formula) but ignores resting HR entirely. The Karvonen method accounts for heart rate reserve (max HR minus resting HR), producing a range that adjusts for fitness level. The lactate-threshold-derived estimate uses a fraction of estimated max HR to approximate where blood lactate begins accumulating. A measured max HR removes the age-formula error from the three methods that use max HR (Maffetone uses none); the methods still differ because they define Zone 2 differently, so use the talk test to choose within the spread.
Should I use the 220-minus-age formula or the Tanaka formula for max heart rate?
The Tanaka formula (208 - 0.7 x age), published by Tanaka, Monahan, and Seals in 2001 in the Journal of the American College of Cardiology, is more accurate than 220-age, particularly for adults over 40. The traditional 220-age formula was never derived from original research but was an approximation that appeared in published guidelines without rigorous validation. For a 50-year-old, 220-age predicts max HR of 170 bpm while Tanaka predicts 173 bpm. The difference grows with age: at 60, 220-age gives 160 while Tanaka gives 166 bpm. Neither formula replaces an actual graded exercise test, which is the gold standard and can reveal individual max HR values that deviate by 10-20 bpm from any formula. The calculator uses 220 − age by default, as the Heart Rate Zone Calculator does, switches to Tanaka when you pick it, and uses your measured max over both.
How do I verify that I am actually training in Zone 2?
Two practical checks and one lab test. The talk test: you should be able to speak in full, continuous sentences without needing to pause for breath; if you can only manage short phrases, you are above Zone 2. Heart rate monitor: a chest strap (more reliable than a wrist sensor during exercise) confirms you are within your calculated range. For a direct answer, a lactate test at a sports medicine clinic finds the heart rate where blood lactate starts to rise, which marks the top of your Zone 2.
How much Zone 2 training should I do per week?
There is no single proven dose. Elite endurance athletes do most of their training, often around 80%, at low intensity (Seiler and Kjerland, 2006). For health, WHO guidelines call for 150-300 minutes of moderate activity a week, and Zone 2 work counts toward that. Three or four sessions of 45-60 minutes is a common coaching prescription that fits inside the WHO range. Brisk walking, easy cycling, swimming, rowing and the elliptical all work.
How quickly will I see results from Zone 2 training?
Expect weeks to months, faster if you are starting from little training. The practical sign is your pace or power at the same Zone 2 heart rate creeping up over a few months of consistent work, and resting heart rate often drifts down. Gains slow as you get fitter. Re-run the calculator when your resting heart rate changes by a few beats.
Can Zone 2 training help with fat loss?
Zone 2 burns a larger share of its calories from fat than harder exercise, but fewer calories per minute, and fat loss depends on total energy balance, not on which fuel you burn during the session. Its advantage is volume: easy sessions are sustainable for long durations and recover quickly, so they add up over a week. Pair them with a calorie deficit from nutrition; the Walking Calorie Calculator and TDEE Calculator estimate the energy side.
Is this tool free and private?
Yes. All calculations run client-side in your browser. No data leaves your device. No signup or account required.
The formula, worked through
- Formula Heart Rate Zone Formula (Karvonen)
Heart rate zone formula (Karvonen): target_HR = (HRmax − HRrest) × intensity_pct + HRrest. HRmax ≈ 208 − 0.7·age (Tanaka).
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Background on the Zone 2 Heart Rate Calculator
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Heart rate zone examples for fat loss, endurance, and peak performance. Real scenarios for busy professionals, runners, and rehabilitation patients.
Articles
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Use it from code
The same calculation as a JavaScript module you can import. It runs where you import it, with no request, key or rate limit.
import { compute } from "https://aifithub.io/engines/zone-2-heart-rate-calculator.js";Input and output contract, TypeScript types and the guide for agents.