Your target heart rate zone is a range of beats per minute that tells you how hard to push during exercise. To find it, you need two numbers: your maximum heart rate and the percentage of that max you want to train at. The whole process takes about two minutes with simple math.
Estimate Your Maximum Heart Rate
The quickest way to estimate your maximum heart rate is the Fox formula: 220 minus your age. A 40-year-old gets a max of 180 beats per minute (bpm). A 55-year-old gets 165 bpm. It’s not perfect, and it tends to underestimate max heart rate in older adults, but it’s the most widely used starting point.
A slightly more accurate alternative is the Tanaka formula: 208 minus (0.7 times your age). For that same 40-year-old, the result is 180 bpm, identical in this case. But for a 60-year-old, the Fox formula gives 160 while the Tanaka formula gives 166. The gap widens with age, and the Tanaka version generally tracks closer to reality for people over 50.
Neither formula is exact. Individual max heart rates can vary by 10 to 15 bpm in either direction. These formulas give you a working estimate, not a lab result.
Measure Your Resting Heart Rate
If you want the most personalized target zone, you’ll also need your resting heart rate. The best time to measure it is right when you wake up in the morning, before getting out of bed. Place two fingers on your wrist or the side of your neck, count the beats for 15 seconds, and multiply by four. Do this for a few mornings and average the results. Most healthy adults land between 60 and 100 bpm, though fit individuals often sit in the 50s or lower.
The Simple Percentage Method
The most straightforward way to find your target zone is to multiply your estimated max heart rate by the percentage range you’re aiming for. The American Heart Association defines moderate-intensity exercise as 50% to 70% of your max and vigorous exercise as 70% to 85%.
Here’s what that looks like for a 35-year-old with a max of 185 bpm:
- Moderate intensity (50%–70%): 93 to 130 bpm
- Vigorous intensity (70%–85%): 130 to 157 bpm
This method works well for general fitness. If you’re walking briskly or doing a steady bike ride, aim for the moderate range. If you’re running, doing intervals, or pushing through a hard cycling session, aim for the vigorous range.
The Karvonen Method for a More Precise Zone
The Karvonen method accounts for your fitness level by factoring in your resting heart rate. It uses something called heart rate reserve, which is simply your max heart rate minus your resting heart rate. You then multiply that reserve by your target percentage and add your resting heart rate back in.
The formula: (max heart rate – resting heart rate) × target percentage + resting heart rate.
Take a 45-year-old with a resting heart rate of 65 bpm. Their estimated max is 175. Their heart rate reserve is 175 minus 65, which equals 110. To find the low end of a 60% to 80% training zone:
- Low end (60%): 110 × 0.60 + 65 = 131 bpm
- High end (80%): 110 × 0.80 + 65 = 153 bpm
This method is more personalized because two people the same age can have very different resting heart rates. Someone with a resting rate of 55 will get a different, and more appropriate, target zone than someone sitting at 75. Cardiac rehab programs commonly use this approach at intensities of 60% to 80% of heart rate reserve.
The Five Heart Rate Zones
If you use a fitness watch or train with a specific plan, you’ll often see heart rate broken into five zones based on percentage of max. Each zone serves a different purpose.
- Zone 1 (50%–60% of max): Warm-ups, cool-downs, and recovery workouts. You can hold a full conversation easily.
- Zone 2 (60%–70% of max): Longer, steady cardio that builds endurance. This is where most of your aerobic base develops. You can still talk in complete sentences.
- Zone 3 (70%–80% of max): A moderate push that builds both strength and endurance. Talking becomes harder, limited to shorter phrases.
- Zone 4 (80%–90% of max): Hard effort that improves speed and power. You can manage only a few words at a time.
- Zone 5 (90%–100% of max): All-out effort, sustainable for only short bursts. This strengthens your heart at peak capacity and builds fast-twitch muscle fibers.
Most people benefit from spending the majority of their training time in zones 2 and 3, with occasional sessions in zones 4 and 5. Zone 1 is useful on rest days when you still want to move.
Quick Reference by Age
Here are the moderate-intensity (50%–70% of max) and vigorous-intensity (70%–85% of max) ranges using the Fox formula, rounded to the nearest whole number:
- Age 25 (max 195): Moderate 98–137, Vigorous 137–166
- Age 30 (max 190): Moderate 95–133, Vigorous 133–162
- Age 35 (max 185): Moderate 93–130, Vigorous 130–157
- Age 40 (max 180): Moderate 90–126, Vigorous 126–153
- Age 45 (max 175): Moderate 88–123, Vigorous 123–149
- Age 50 (max 170): Moderate 85–119, Vigorous 119–145
- Age 55 (max 165): Moderate 83–116, Vigorous 116–140
- Age 60 (max 160): Moderate 80–112, Vigorous 112–136
- Age 65 (max 155): Moderate 78–109, Vigorous 109–132
- Age 70 (max 150): Moderate 75–105, Vigorous 105–128
When Heart Rate Zones Don’t Work
Heart rate formulas assume a typical cardiovascular response to exercise. Several common situations throw them off. Beta-blockers, prescribed for high blood pressure and other heart conditions, slow your heart rate and can prevent it from climbing to your normal target zone during a workout. If you take beta-blockers and try to hit a number-based target, you may push dangerously hard trying to reach a zone your medication won’t let you reach.
In these cases, perceived exertion is a better guide. The Borg Rating of Perceived Exertion scale runs from 6 (no exertion at all) to 20 (maximum effort). A rating of 12 to 14 reflects moderate intensity, roughly equivalent to “somewhat hard.” At this level, the exercise takes real effort but you can sustain it and still carry on a choppy conversation. If you can’t talk at all while exercising, you’re likely working too hard regardless of what the numbers say.
Caffeine, dehydration, stress, and lack of sleep can also inflate your heart rate without reflecting actual workout intensity. If your heart rate seems unusually high on a given day and the effort feels easy, trust the effort over the number.
How to Track During a Workout
A chest strap heart rate monitor gives the most accurate real-time readings during exercise. Wrist-based optical sensors on smartwatches have improved significantly but can lag during fast-changing intervals or read inaccurately if the watch shifts on your wrist.
If you don’t have a device, the manual pulse check works fine. Pause briefly, find your pulse at your wrist or neck, count beats for 15 seconds, and multiply by four. This is practical for steady-state cardio like jogging or cycling but less useful during intervals when your heart rate is changing rapidly.
The talk test remains one of the simplest, most reliable intensity checks. During moderate exercise, you should be able to speak in sentences but not sing. During vigorous exercise, you can get out only a few words between breaths. It costs nothing, requires no equipment, and works even when medications or individual variation make heart rate numbers unreliable.