For most people, a good target during exercise is 50% to 85% of your maximum heart rate, depending on how hard you want to push. That translates to roughly 95 to 162 beats per minute for a 35-year-old, or 85 to 145 bpm for a 50-year-old. The right number for you depends on your age, your fitness goals, and how intense you want your workout to be.
How to Find Your Maximum Heart Rate
Every target heart rate zone is based on your estimated maximum heart rate, so that number comes first. The simplest and most widely used formula is 220 minus your age. If you’re 40, your estimated max is 180 bpm. If you’re 30, it’s 190.
That formula (developed by Fox, Naughton, and Haskell in 1971) has a known weakness: it tends to underestimate max heart rate in older adults. A newer formula, developed by Tanaka and colleagues, adjusts for this: 208 minus 0.7 times your age. For a 40-year-old, that gives 180 (same result). But for a 60-year-old, the older formula predicts 160 while the Tanaka formula predicts 166, a meaningful difference when you’re calculating training zones.
Both formulas can be off by 10 to 12 beats per minute in either direction. They’re population averages, not personalized measurements. If you want a precise number, a graded exercise test on a treadmill or bike is the gold standard.
The Five Heart Rate Zones
Heart rate zones divide the range between rest and your maximum into five tiers. Each one feels different and trains your body differently.
- Zone 1 (50% to 60% of max): Easy effort. You can hold a full conversation without pausing. This is warm-up, cool-down, and recovery territory.
- Zone 2 (60% to 70% of max): Light effort. You can talk but might need to pause for a breath between sentences. This is the zone for longer cardio sessions that build endurance, like a steady jog or an easy bike ride.
- Zone 3 (70% to 80% of max): Moderate effort. Talking drops to short phrases. The work feels comfortably hard, and you’re building both strength and aerobic fitness.
- Zone 4 (80% to 90% of max): Hard effort. Speaking takes real work. You’re pushing toward your limit, building speed and power.
- Zone 5 (90% to 100% of max): All-out effort. You can barely breathe, let alone talk. This is sprint territory, sustainable for only short bursts. It strengthens the heart at peak capacity and builds fast-twitch muscle fibers.
The American Heart Association defines moderate-intensity exercise as 50% to 70% of max (roughly Zones 1 through 3) and vigorous exercise as 70% to 85% (Zones 3 through 4). Most general fitness guidelines recommend spending the bulk of your workout time in the moderate range, with shorter periods at higher intensities if your fitness level supports it.
Target Ranges by Age
Here’s what moderate (50% to 70%) and vigorous (70% to 85%) zones look like at different ages, using the 220-minus-age formula:
- Age 25: Max 195. Moderate: 98 to 137 bpm. Vigorous: 137 to 166 bpm.
- Age 35: Max 185. Moderate: 93 to 130 bpm. Vigorous: 130 to 157 bpm.
- Age 45: Max 175. Moderate: 88 to 123 bpm. Vigorous: 123 to 149 bpm.
- Age 55: Max 165. Moderate: 83 to 116 bpm. Vigorous: 116 to 140 bpm.
- Age 65: Max 155. Moderate: 78 to 109 bpm. Vigorous: 109 to 132 bpm.
These are starting points. Your actual working range may sit a bit higher or lower depending on your fitness level, medications, and genetics.
A More Personalized Calculation
The basic percentage-of-max approach ignores one important variable: your resting heart rate. Someone with a resting rate of 55 bpm has a much wider working range than someone resting at 80 bpm, even if they’re the same age.
The Karvonen method (also called heart rate reserve) accounts for this. First, subtract your resting heart rate from your max. That gives you your heart rate reserve, the total range your heart can ramp up during effort. Then multiply that reserve by the percentage you’re targeting and add your resting heart rate back.
For example, a 40-year-old with a resting heart rate of 65 bpm and an estimated max of 180: heart rate reserve is 115 bpm. To find the lower end of a moderate zone (50%), multiply 115 by 0.50, which gives 57.5, then add the resting rate of 65. That’s about 123 bpm. The upper end of vigorous (80%) would be 115 times 0.80 plus 65, or 157 bpm. Compare that to the simpler method, which would give a moderate floor of just 90 bpm for this person. The Karvonen approach produces a target that better reflects individual fitness.
Which Zone Should You Train In?
That depends entirely on your goal. If you’re building a general aerobic base, improving heart health, or training for a long-distance event, Zone 2 is your workhorse. It’s the intensity where your body gets efficient at burning fat for fuel and where you can accumulate a lot of training volume without breaking down. Most experienced endurance coaches recommend spending 70% to 80% of total training time in this zone.
If you’re trying to improve speed, raise your anaerobic threshold, or get more bang for less time, intervals in Zones 4 and 5 are effective. High-intensity interval training alternates between bursts in these upper zones and recovery periods in Zones 1 or 2. Even two sessions per week of this type of training can produce significant cardiovascular gains.
For general health, the simplest benchmark comes from the American Heart Association: aim for the moderate range (50% to 70% of max) for at least 150 minutes per week, or the vigorous range (70% to 85%) for at least 75 minutes per week.
Why Your Heart Rate Monitor Might Be Off
If you’re tracking heart rate with a wrist-worn device, accuracy varies more than you might expect. A study comparing commercial monitors against medical-grade ECG found that chest straps were the most accurate, with agreement rates around 98%. Wrist-worn devices like the Apple Watch performed well overall (96% agreement), but accuracy dropped as exercise intensity increased. At high treadmill speeds (8 to 9 mph), none of the wrist-worn devices maintained strong agreement with the ECG reading.
Some devices consistently over- or underestimate. In the same study, one wrist device overestimated heart rate by an average of 6 bpm, while another underestimated by about 2 bpm. If you’re making training decisions based on narrow zone targets, a chest strap gives you the most reliable data. For general fitness tracking, a well-reviewed wrist device is usually close enough.
When Standard Formulas Don’t Apply
Beta-blockers and certain other blood pressure medications slow the heart rate by design. If you take one, you may never reach your calculated target heart rate no matter how hard you exercise. That doesn’t mean the workout isn’t effective. It means the standard formulas aren’t calibrated for your situation.
One practical alternative is a perceived exertion scale, where you rate how hard the workout feels on a scale from 6 (no effort) to 20 (absolute maximum). A moderate workout typically falls around 12 to 14. A vigorous one registers 15 to 17. This approach bypasses heart rate entirely and focuses on how your body actually responds to the effort. If you’re on medications that affect heart rate, an exercise stress test can also help establish a personalized target range.
The Talk Test as a Simple Check
If you don’t have a monitor and don’t want to do math, the talk test maps surprisingly well onto the heart rate zones. If you can speak in full sentences without pausing for breath, you’re in the light-to-moderate range. If you can get out a few words at a time but need to breathe between phrases, you’re in the vigorous range. If you can’t speak at all, you’re at or near your max. It’s not precise, but it’s a reliable gauge that works for anyone, regardless of age, fitness, or medication.