Calculate your personalized training zones.
Enter your age, resting heart rate plus any other of the variables you know. If you have tested your maximum heart rate, enter it. If not, don’t worry, we use the latest research to estimate your maximum heart rate. If you know your threshold heart rate, you can enter it. Gender can affect the heart rate zones so enter your sex and your current fitness level is also helpful. Then, hit Calculate My Zones.
The McMillan calculator splits your heart rate range into six zones rather than the standard five. Here’s what each zone is for and what it should feel like.
Feels likeVery easy, full conversation, almost walking.
Best forActive recovery between hard efforts.
Sample workout15–30 min of very slow jogging between intervals.
Feels likeConversational, you could chatter all day.
Best forBuilding aerobic engine and fat oxidation.
Sample workout45–90 min easy run, weekly long run.
Feels likeEasy-medium to medium effort.
Best forBeginning lactate threshold work.
Sample workout25–45 min steady-state run.
Feels like"Comfortably hard" — 3–5 word answers.
Best forPushing lactate threshold to a faster pace.
Sample workoutTempo runs of 15–30 minutes.
Feels likeMedium-hard, controlled.
Best forFaster threshold adaptations.
Sample workout3–8 min repeats with short jog recovery.
Feels likeHard, heavy breathing.
Best forVO2max and neuromuscular speed.
Sample workout400m–2000m repeats at 5K-3K pace.
The McMillan system uses six zones instead of the standard five because lactate threshold training needs more precision than a single zone provides — some workouts should sit just below threshold, some right at it, and some slightly above. Splitting that training zone into three (zones 3, 4, and 5) gives you the control that actually moves your threshold pace.
Heart rate zones are calculated as a percentage of either your maximum heart rate, your heart rate reserve (HRR), or your lactate threshold heart rate. The McMillan calculator uses the heart rate reserve method (Karvonen formula), which produces more personalized zones than plain max-HR percentages because it accounts for your resting heart rate too. The McMillan system uses six zones, ranging from Zone 1 Recovery Jogs (55-65% HRR) up to Zone 6 Speed and Sprint Workouts (90-100% HRR).
The most accurate zone calculator uses the heart rate reserve (Karvonen) method — which the McMillan heart rate calculator uses. This method is very accurate and simply requires your max HR and resting HR, both of which you can measure at home. Age-based formulas alone can be off by 10-30 bpm and are the least reliable method.
Start with an age-based estimate as a rough ballpark — the Tanaka formula (208 − 0.7 × age) tends to be more accurate than the traditional 220-minus-your-age. Then validate with the McMillan Field Test: after a thorough warm-up, run four 1-minute progressive repeats on flat ground (each harder than the last), then immediately do 3-4 maximum-effort hill repeats until your heart rate plateaus across consecutive efforts. That plateau is your real max HR. Formulas alone can be off by 10-30 bpm for any individual.
Zone 2 is the aerobic training zone — your easy and long run pace. In the McMillan system, Zone 2 sits at 55-78% of your heart rate reserve (HRR), which typically feels conversational — you can hold a full conversation with another runner. Zone 2 training builds your aerobic engine, improves fat utilization, and makes up the bulk of a distance runner’s weekly training volume.
Heart rate can be a good metric for monitoring your training. I find it especially helpful on easy runs where you don’t want to run too fast. I also find it very useful for lactate threshold training. In fact, it’s so helpful for threshold training that, unlike other coaches, I divide that training zone into multiple heart rate zones in the McMillan system — for more precise control of pace relative to your threshold.
Heart rate is not helpful in hot or humid conditions, because the heart rate is elevated to address the heat load and is no longer reflective of the exercise stress. Heart rate is also not helpful for short repetitions (lasting less than two minutes) like speed and sprint workouts — the repetition is over before the heart rate reaches a steady state. That said, some runners and coaches use heart rate during the recovery interval as a way to track increasing fitness, indicated by a faster drop in heart rate between repetitions.
Running max HR is typically 5-10 bpm higher than cycling max HR for the same athlete, because running recruits more total muscle mass. If you train in both sports, calculate separate heart rate zones for each using sport-specific max HR or lactate threshold values. Using your running zones on the bike will put your cycling workouts at the wrong effort levels.
Yes. The McMillan Heart Rate Zone Calculator is completely free to use and requires no signup. Enter your age and resting heart rate (plus optional max HR, threshold HR, gender, and fitness level) and your six personalized zones calculate instantly.
