Find your Zone 2 aerobic base-training heart rate range using three different methods — percentage of max HR, Karvonen (heart rate reserve), and the Maffetone MAF 180 formula — so you can train at a genuinely easy, sustainable, conversational pace.
Zone 2 is a deliberately easy, low-intensity training pace — roughly 60-70% of your maximum heart rate — that endurance runners, cyclists, triathletes and rowers use to build their aerobic base. It's often described as "conversational pace": if you can comfortably hold a chat in full sentences while training, you're likely in the right zone. Rather than chasing a single number, this calculator gives you three separate ways to estimate your own Zone 2 range, because different methods use different information about you and can land in noticeably different places.
| Method | BPM Range | Basis |
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All three methods below try to answer the same question — "what heart rate counts as easy aerobic effort for me?" — but each one uses a different piece of information and a different assumption, which is why they don't produce identical numbers. Method 1 only needs your maximum heart rate. Method 2 (Karvonen) also factors in your resting heart rate, which generally shifts the range upward and makes it more specific to you. Method 3 (MAF) doesn't use your max heart rate at all — it works from your age and a category describing your recent training and health history.
It's normal for these three ranges to sit apart from each other, sometimes by a noticeable margin. Karvonen, when it's built on a resting heart rate you actually measured rather than guessed, is generally regarded as more personalised than a flat percentage of max HR, because it accounts for more of your individual cardiovascular profile. The Maffetone MAF formula is widely used and popular, particularly among runners and triathletes, but its adjustment categories come from accumulated coaching experience and community practice rather than from a single physiological study — it's a practical, factual tool, not a more "scientific" one than the other two.
Zone 2 gets its reputation as the foundation of endurance training because it's the intensity at which your body relies heavily on fat and oxygen to produce energy, rather than leaning on the faster but more limited anaerobic systems. Spending consistent time at this easy effort is thought to encourage your body to grow more small blood vessels, build more of the energy-producing structures inside your muscle cells, and become generally more efficient at using oxygen — improvements that quietly raise the ceiling for everything else you do, including your harder sessions. It's also a pace your body can sustain for a long time without digging into a deep recovery hole, which is exactly why so many structured training plans stack a large share of weekly volume into this zone rather than spreading effort evenly across every intensity. None of this means hard training doesn't matter — it means the easy days are doing real, specific work of their own, even though they don't always feel like it.
What is Zone 2 training?
Zone 2 is a low-intensity aerobic training zone, generally 60-70% of your maximum heart rate, where the effort feels comfortably easy rather than hard. It's called "base training" because sustained time at this intensity is thought to build the aerobic engine — more capillaries, more mitochondria and a stronger aerobic enzyme response — that higher-intensity sessions later draw on. Most structured endurance programs, from beginner running plans to professional cycling training blocks, include a large proportion of Zone 2 work.
How do I know I'm in Zone 2 without a heart rate monitor?
The simplest check is the "talk test": if you can hold a full conversation in complete sentences without gasping for air, you're likely in or near Zone 2. If you can only get out a few words at a time, you've probably drifted into a higher zone. It's a rough guide rather than a precise measurement, but it's a useful sanity check if you're training without a heart rate monitor or don't trust the numbers on a given day.
Why do the three methods on this page give different numbers?
Each method estimates Zone 2 using a different piece of information and a different assumption. The %Max HR method only needs your maximum heart rate and applies a flat 60-70% band. Karvonen also factors in your resting heart rate, which shifts the range upward for most people. The MAF 180 method doesn't use max heart rate at all — it starts from 180 minus your age and applies a community-based adjustment for your training history. Getting three different ranges from three different starting assumptions is expected, not a sign that something is wrong.
Which method is most accurate?
None of the three is definitively "correct" — they're different estimation approaches built on different assumptions. Karvonen is generally considered the most personalised of the three when you use an actual measured resting heart rate rather than a guess, because it accounts for more of your individual physiology than a flat percentage of max HR. The MAF formula is popular in running and triathlon communities but its adjustment categories come from accumulated coaching experience rather than a single physiological study. The most reliable option, if you want a genuinely precise number, is a lab-based lactate or ventilatory threshold test.
How much of my training should be in Zone 2?
Many endurance coaches and the "polarized training" model suggest that the large majority of weekly training volume — often cited as somewhere around 80% — sits in low-intensity zones like Zone 2, with a smaller portion spent at high intensity and comparatively little time in the uncomfortable middle zones. Exact proportions vary by sport, event distance and individual, so this is a general pattern rather than a fixed rule everyone must follow.
Can beginners use Zone 2 training?
Yes — in fact Zone 2 is often a particularly good starting point for beginners, since the low intensity keeps the physical and joint stress manageable while still building aerobic fitness. New exercisers may find their Zone 2 pace is quite slow at first (a brisk walk rather than a jog, for example), which is completely normal; the pace needed to stay in Zone 2 typically increases as aerobic fitness improves.
What's the difference between Zone 2 and the MAF method?
"Zone 2" usually refers to the 60-70% of max heart rate band calculated from your maximum or heart rate reserve. "MAF" (Maffetone's 180-age formula) is a separate, self-contained method that produces its own ceiling and a 10 bpm window below it, without referencing your max heart rate at all. In practice the two often land in a similar general area for many people, which is why MAF is frequently described as a way of estimating a Zone 2-like training range, but they're calculated independently and can diverge, especially for people with unusually high or low measured max heart rates.
What are the limitations of formula-based heart rate zones compared to lab testing?
All three formulas on this page are population-based estimates, not measurements of your individual physiology. Your true maximum heart rate can differ from the Tanaka estimate by ten beats per minute or more in either direction, and formulas can't account for things like medication, heat, altitude, illness or accumulated fatigue on a given day. A laboratory test that measures lactate or gas exchange during a graded exercise test gives a genuinely individual result, while formula-based zones are a practical, free starting point that most recreational athletes use instead.