Your target heart rate is the range your heart should beat within during exercise to get the most benefit from your workout. It’s expressed as a percentage of your maximum heart rate, typically between 50% and 85%, and it shifts depending on how intensely you’re exercising. Knowing your target range helps you gauge whether you’re pushing hard enough to improve fitness or backing off enough to stay safe.
How to Calculate Your Target Heart Rate
The starting point is your estimated maximum heart rate, which is the fastest your heart can beat during all-out effort. The simplest formula: subtract your age from 220. A 40-year-old, for example, has an estimated max of 180 beats per minute (bpm). Your target heart rate is then a percentage of that number, depending on how hard you want to work.
The American Heart Association breaks it into two main zones:
- Moderate intensity: 50% to 70% of your maximum heart rate
- Vigorous intensity: 70% to 85% of your maximum heart rate
For that 40-year-old with a max of 180 bpm, moderate exercise means keeping the heart rate between 90 and 126 bpm. Vigorous exercise means 126 to 153 bpm. Here’s a quick reference for common ages:
- Age 25: Max 195 bpm, moderate zone 98–137, vigorous zone 137–166
- Age 35: Max 185 bpm, moderate zone 93–130, vigorous zone 130–157
- Age 45: Max 175 bpm, moderate zone 88–123, vigorous zone 123–149
- Age 55: Max 165 bpm, moderate zone 83–116, vigorous zone 116–140
- Age 65: Max 155 bpm, moderate zone 78–109, vigorous zone 109–132
Why the Standard Formula Isn’t Perfect
The 220-minus-age formula first appeared in a 1970 review paper, and its exact origins are surprisingly murky. While it’s easy to remember, it can be off by as much as 9 bpm on average. It tends to overestimate maximum heart rate in younger adults and underestimate it in older adults, only landing close to accurate for people in their 30s.
A more refined alternative is the Tanaka formula: 208 minus (0.7 times your age). Developed from a meta-analysis of 351 studies involving over 18,000 people, it performs more consistently across age groups and between men and women, with differences of roughly 1 bpm between sexes. For a 50-year-old, the standard formula predicts a max of 170, while the Tanaka formula predicts 173. The gap widens at the extremes of age.
Neither formula accounts for individual fitness, genetics, or health conditions. If you want a truly personalized number, a graded exercise test supervised by a professional will measure your actual max heart rate directly.
Heart Rate Reserve: A More Personalized Approach
Another method, sometimes called the Karvonen method, factors in your resting heart rate to give a more tailored target. Your heart rate reserve is the difference between your maximum heart rate and your resting heart rate. A fit person with a low resting heart rate of 55 bpm and a max of 180 bpm has a reserve of 125 bpm. Someone less conditioned with the same max but a resting rate of 80 bpm has a reserve of only 100 bpm.
To find your target using this method, multiply your heart rate reserve by the desired intensity percentage, then add your resting heart rate back in. If you’re aiming for 60% intensity with a reserve of 125 and a resting rate of 55: (125 × 0.60) + 55 = 130 bpm. This approach better reflects your actual cardiovascular fitness because it accounts for where your heart starts, not just where it tops out.
What Each Intensity Zone Does for You
Not all heart rate zones deliver the same results. Training at different intensities triggers different adaptations in your body, and mixing zones throughout the week produces better overall fitness than staying at one level.
At lower intensities, around 60% to 70% of your max (often called zone 2), your body primarily burns fat for fuel. This is the range for longer, steadier workouts that build endurance without heavy strain. A brisk walk, an easy bike ride, or a light jog typically falls here. You can hold a conversation comfortably. This zone is ideal for building an aerobic base and reducing injury risk.
At higher intensities, around 80% to 90% of your max (zone 4), your body shifts to burning carbohydrates and protein. You’re pushing hard, close to your redline, and this kind of effort builds speed and strength. Think hill sprints, fast intervals, or competitive efforts. You can manage only a few words between breaths. These sessions are shorter by necessity and need recovery time afterward.
The moderate zone, 50% to 70%, is what most health guidelines emphasize. Federal recommendations suggest building up to 2 hours and 30 minutes per week at moderate intensity, or 1 hour and 15 minutes at vigorous intensity, to maintain cardiovascular health.
How to Check Your Heart Rate During Exercise
The simplest method is pressing two fingers against the inside of your wrist or the side of your neck, counting beats for 15 seconds, and multiplying by four. Wrist-based fitness trackers and chest strap monitors automate this, though accuracy varies by device. Chest straps tend to be more reliable during high-intensity movement.
If tracking your pulse feels impractical, you can use perceived exertion instead. The Borg scale rates how hard exercise feels on a scale from 6 (no effort at all) to 20 (absolute maximum). A rating between 12 and 14 corresponds roughly to moderate intensity. On a simpler 0-to-10 version, moderate effort falls around 4 to 5, and vigorous effort around 6 to 7. The talk test works too: if you can speak in full sentences, you’re likely in the moderate zone. If you can only get out a few words, you’ve crossed into vigorous territory.
When Target Heart Rate Formulas Don’t Apply
Beta blockers and certain other blood pressure medications slow the heart rate by design. If you take one, your heart physically cannot speed up the way it normally would during exercise. You may never reach the target heart rate a formula predicts, no matter how hard you push. In that case, perceived exertion becomes a far more useful guide than any number on a watch.
People with cardiac conditions, those recovering from heart surgery, or anyone on medications that affect heart rhythm should work with their care team to establish a personalized target range. The standard formulas assume a healthy cardiovascular system and no pharmaceutical influence on heart rate. Certain conditions like atrial fibrillation also make pulse counting unreliable because the rhythm itself is irregular, and the number you count may not reflect how hard your heart is actually working.
Caffeine, dehydration, heat, and altitude can all temporarily raise your heart rate independent of effort. A heart rate of 150 bpm on a hot, humid day may represent less actual cardiovascular work than the same 150 bpm in a cool gym. Context matters when interpreting the numbers.