Finding your heart rate zones starts with two numbers: your maximum heart rate and your resting heart rate. From there, simple math divides your full cardiac range into five training zones, each tied to a different level of effort and a different fitness benefit. The process takes about five minutes with a calculator, or you can let a fitness watch do it automatically once you feed it the right inputs.
Estimate Your Maximum Heart Rate
Your maximum heart rate (MHR) is the ceiling for all your zone calculations. The simplest formula, and the one most apps default to, is 220 minus your age. A 40-year-old gets a max of 180 beats per minute. It’s easy to remember, but it can be off by 10 to 12 beats per minute in either direction, which ripples through every zone you calculate from it.
A more refined formula, developed from a meta-analysis of over 18,000 people, is 208 minus 0.7 times your age. For that same 40-year-old, the result is 180, but the two formulas diverge more at younger and older ages. A 25-year-old gets 195 from the simple formula but 190.5 from the revised one. A 60-year-old gets 160 versus 166. If you’re under 30 or over 50, the revised formula tends to be closer to reality.
Women may get better accuracy from a sex-specific formula: 201 minus 0.63 times your age. Men can use 208 minus 0.8 times your age. These were designed to account for the fact that women’s heart rates decline a bit more slowly with age than men’s.
No formula is perfect because genetics, fitness level, and medications all shift your true max. If precision matters to you (say, for race training), a graded exercise test at a sports medicine clinic will give you an exact number.
Measure Your Resting Heart Rate
Your resting heart rate is the other half of the equation if you want personalized zones. The best time to measure it is first thing in the morning, before you get out of bed, on a day when you haven’t had alcohol the night before and aren’t stressed or sick. Place two fingers on the inside of your wrist or the side of your neck, count the beats for 30 seconds, and double the number. Do this on three or four consecutive mornings and average the results. Most adults land between 60 and 80 beats per minute, though well-trained endurance athletes can sit in the low 40s or even high 30s.
If you wear a fitness tracker overnight, it likely logs your resting heart rate automatically. Use the average over a week rather than any single reading.
The Simple Method: Percentage of Max
The most straightforward way to set zones is to multiply your max heart rate by the percentage range for each zone. Here’s the standard five-zone model:
- Zone 1 (50% to 60% of max): Warm-ups, cool-downs, and recovery days. You can hold a full conversation without pausing for breath.
- Zone 2 (60% to 70% of max): Easy, sustained effort that builds aerobic endurance. You can talk but may need to pause between sentences. This is the zone most coaches recommend for the bulk of your weekly training.
- Zone 3 (70% to 80% of max): A “comfortably hard” pace. Conversation drops to short phrases. Builds both strength and endurance.
- Zone 4 (80% to 90% of max): Hard effort that improves speed and power. Talking takes real effort. Sustainable for roughly 20 to 40 minutes in trained individuals.
- Zone 5 (90% to 100% of max): All-out intensity. You’re gasping, not chatting. This zone trains your heart at peak capacity and recruits fast-twitch muscle fibers. Most people can hold it for only a few minutes at a time.
For a 35-year-old using the 220-minus-age formula (max of 185), Zone 2 runs from 111 to 130 bpm, and Zone 4 runs from 148 to 167 bpm. The American Heart Association defines moderate-intensity exercise as 50% to 70% of max and vigorous exercise as 70% to 85%, which maps roughly to Zones 2 through 4.
The More Accurate Method: Heart Rate Reserve
The percentage-of-max approach treats everyone with the same max heart rate identically, regardless of fitness. Someone with a resting heart rate of 50 and someone with a resting rate of 80 would get the same zones, even though their hearts have very different working ranges. The heart rate reserve method (also called the Karvonen method) fixes this by factoring in your resting heart rate.
Here’s how it works, step by step:
First, calculate your heart rate reserve: maximum heart rate minus resting heart rate. For a 35-year-old with a max of 185 and a resting rate of 65, that’s 120 bpm of reserve.
Next, multiply that reserve by the low and high percentages of the zone you want, then add your resting heart rate back to each result. For Zone 2 (60% to 70%):
- Low end: (120 × 0.60) + 65 = 137 bpm
- High end: (120 × 0.70) + 65 = 149 bpm
Notice that Zone 2 lands at 137 to 149 bpm using this method, compared to 111 to 130 bpm using the simple percentage. That’s a meaningful difference. The Karvonen method produces higher zone floors because it accounts for the fact that your heart is already beating at rest, so the “easy” portion of your range isn’t truly available for training stimulus. For most exercisers, this gives a more realistic picture of what each effort level actually feels like.
Repeat the math for each zone and you’ll have a complete, personalized set of five ranges.
Field-Test Your Threshold Directly
If you’re a runner or cyclist training for performance, formulas may not be precise enough. A 30-minute time trial can reveal your lactate threshold heart rate, the point where your body shifts from primarily aerobic to increasingly anaerobic energy production. Your training zones are then built around that threshold rather than an estimated max.
The protocol is straightforward. After a thorough warm-up (10 to 15 minutes of easy effort plus a couple of short accelerations), go as hard as you can sustain for 30 minutes. Ten minutes into the effort, hit the lap button on your heart rate monitor. Your average heart rate over the final 20 minutes is your approximate lactate threshold. Some coaches recommend subtracting 3% to 5% from that number if you’re using a 30-minute test rather than a full 60-minute effort.
Once you have a threshold heart rate, training platforms like TrainingPeaks and most cycling apps will auto-generate zones based on percentages of that number rather than percentages of your max. This approach is popular in triathlon and cycling coaching because it reflects your actual fitness, not just your age.
Using Perceived Exertion Without a Monitor
You don’t need a chest strap or smartwatch to train by intensity. The Borg Rating of Perceived Exertion scale runs from 6 (no effort at all) to 20 (absolute maximum). A rating of 12 to 14 corresponds to moderate or “somewhat hard” effort, roughly equivalent to Zones 2 and 3. A rating of 15 to 17 maps to hard or “very hard” effort, landing in Zone 4 territory. Anything above 18 is Zone 5.
The talk test is an even simpler proxy. If you can sing, you’re in Zone 1. If you can speak in full sentences with occasional pauses, you’re in Zone 2. If you’re limited to a few words at a time, you’re in Zone 4. If you can’t speak at all, you’ve hit Zone 5. These aren’t as precise as a heart rate number, but they’re surprisingly reliable for day-to-day training.
When Standard Zones Don’t Apply
Beta blockers and certain other blood pressure medications lower your heart rate artificially, which means standard zone calculations will overshoot your actual capacity. If you take a beta blocker, your true max heart rate may be 20 to 30 bpm lower than any formula predicts. In that case, perceived exertion becomes your primary intensity guide rather than a backup one. The Borg scale or talk test will track your real effort more accurately than any heart rate number.
Caffeine, dehydration, heat, and altitude all push heart rate higher at the same effort level. If your heart rate is running 10 bpm above normal on a hot day and the effort feels the same, trust the effort. Your zones haven’t changed; your body is just working harder to cool itself.
Fitness also shifts your zones over time. As your cardiovascular system adapts, your resting heart rate drops, your heart rate reserve expands, and the same pace produces a lower heart rate. Recalculating your zones every two to three months (or after a significant block of training) keeps them aligned with your current fitness.