To calculate your heart rate zones, you need one key number: your maximum heart rate. From there, each zone is a simple percentage range. The most common formula estimates your max heart rate as 220 minus your age, but more accurate options exist depending on your sex and fitness goals. Here’s how to do it step by step.
Step 1: Find Your Maximum Heart Rate
Your maximum heart rate (MHR) is the ceiling for all five zones. The simplest estimate is 220 minus your age. If you’re 40, that gives you 180 beats per minute. This formula has been used for decades, but it can be off by 10 to 12 beats per minute in either direction, and it tends to underestimate max heart rate in older adults.
A more accurate formula, developed by researcher Hirofumi Tanaka after a meta-analysis of 351 studies, is: 208 minus (0.7 × your age). For that same 40-year-old, this gives 180. The difference becomes more meaningful as you age. At 60, the standard formula predicts 160, while the Tanaka formula predicts 166. Those six beats shift every zone boundary upward.
For women specifically, research from the St. James Women Take Heart Project produced a separate formula: 206 minus (0.88 × your age). Standard formulas were designed primarily from male data. Using them for women led to overly pessimistic readings during exercise testing, because women have different physiologic responses to exertion. A 45-year-old woman gets a max of 166 from the standard formula, but 166.4 from the women’s formula. The gap widens at younger ages.
Step 2: Apply the Zone Percentages
Once you have your max heart rate, multiply it by the percentage range for each zone:
- Zone 1 (50% to 60% of MHR): Light activity like walking or easy warm-ups. You can hold a full conversation without effort.
- Zone 2 (60% to 70% of MHR): Moderate effort like jogging or easy cycling. You can talk in sentences but notice your breathing.
- Zone 3 (70% to 80% of MHR): Moderate to hard effort. Conversation becomes choppy. Tempo runs and steady-state cardio live here.
- Zone 4 (80% to 90% of MHR): Hard effort. You can manage only a few words at a time. This is interval training territory.
- Zone 5 (90% to 100% of MHR): All-out effort. Sprints and short bursts only. Unsustainable for more than a couple of minutes.
Here’s a worked example for a 35-year-old using the Tanaka formula. Max heart rate: 208 minus (0.7 × 35) = 183.5, rounded to 184. Zone 1 runs from 92 to 110 bpm. Zone 2 is 110 to 129. Zone 3 is 129 to 147. Zone 4 is 147 to 166. Zone 5 is 166 to 184.
A More Personalized Method: Heart Rate Reserve
The percentage-of-max approach treats everyone with the same max heart rate identically. But two 35-year-olds could have very different resting heart rates, one at 55 bpm and another at 75 bpm. The Karvonen method accounts for this by using your heart rate reserve, which is the gap between your max and resting heart rate.
The formula for a target heart rate in any zone is: (heart rate reserve × target percentage) + resting heart rate. Heart rate reserve is simply max heart rate minus resting heart rate.
Take that 35-year-old with a max of 184 and a resting heart rate of 60. Heart rate reserve is 124. To find the bottom of Zone 2 (60%), calculate: (124 × 0.60) + 60 = 134 bpm. The top of Zone 2 (70%) is (124 × 0.70) + 60 = 147 bpm. Compare that to the simpler method, which gave a Zone 2 of 110 to 129. The Karvonen numbers are higher because they factor in your individual fitness baseline. For someone with a low resting heart rate (a sign of cardiovascular fitness), this method tends to push zones upward, reflecting the reality that easy effort for a fit person starts at a higher heart rate than the basic formula suggests.
How to Measure Your Resting Heart Rate
If you want to use the Karvonen method, you need an accurate resting heart rate. The best time to check is first thing in the morning, after a full night of sleep, before you get out of bed or have coffee. Place the tips of your index and middle fingers on the inside of your wrist on the thumb side. Press lightly over the artery, count the beats for 30 seconds, and multiply by two.
Do this for three to five mornings and average the results. A single reading can be skewed by poor sleep, stress, or dehydration. Most adults fall between 60 and 100 bpm at rest. Well-trained endurance athletes often sit in the 40s or 50s.
Using a Field Test Instead of a Formula
Formulas estimate your max heart rate based on age, but your actual max could be significantly different. If you want zones built on real data from your own body, a field test is the better option. One widely used approach is a 30-minute time trial. Go as hard as you can sustain for 30 minutes (running, cycling, or rowing), and record your average heart rate for the last 20 minutes. That number closely approximates your lactate threshold heart rate, the point where your body shifts from primarily aerobic to increasingly anaerobic metabolism.
Lactate threshold heart rate typically falls around 85% to 90% of true max heart rate for trained individuals. You can then build your zones around this anchor point rather than a formula-derived max. Endurance coach Joe Friel recommends repeating this test every four to eight weeks, not because your threshold heart rate changes dramatically, but to track improvements in pace or power at that same heart rate. One important note: lactate threshold varies by sport. If you swim and run, you’ll need separate tests for each.
Expect to be about 5% slower on a solo time trial than you would be in an actual race, because competition adds an intensity boost that’s hard to replicate alone. If you prefer to use a race, choose one long enough to take at least an hour at race effort, and use the average heart rate from the last two-thirds of that effort.
Why Zone 2 Gets So Much Attention
Zone 2 sits just below the intensity where lactate starts building up faster than your body can clear it. Blood lactate levels stay between roughly 1.5 and 2.0 mmol/L, which is low enough that you can exercise for a long time without significant fatigue. At this intensity your body burns fat at its highest rate, depletes very little stored glycogen, and requires minimal recovery afterward.
The deeper benefit is what happens inside your muscle cells. Zone 2 exercise stimulates the growth and efficiency of mitochondria, the structures that produce energy. Over weeks and months, this builds a larger aerobic engine. You become better at using fat for fuel, your endurance improves, and higher-intensity work feels easier because your aerobic base can handle more of the load. This is why many coaches recommend spending 70% to 80% of total training time in Zone 2, saving harder efforts for targeted sessions.
Which Calculation Method to Use
For most people getting started with heart rate training, the percentage-of-max method using the Tanaka formula (208 minus 0.7 times your age) is the simplest and reasonably accurate starting point. Women may get a better estimate from the formula 206 minus 0.88 times their age. If you already know your resting heart rate and want more personalized zones, the Karvonen method is a meaningful upgrade that takes five minutes of extra math. And if you’re a serious runner, cyclist, or triathlete willing to push through 30 hard minutes, a field test will give you the most accurate training zones of all.
Whichever method you choose, treat your zone boundaries as guidelines rather than rigid cutoffs. A beat or two above or below the line doesn’t change the training effect. What matters is spending most of your time in the right general intensity range for your goal, whether that’s building endurance in Zone 2 or sharpening speed in Zone 4.