Whether you are going for a jog, cycling to work, or following a group fitness class, your heart rate tells you how hard your body is actually working. This heart rate calculator estimates your maximum heart rate and breaks it into practical target training zones — so you know exactly where to push and where to hold back.
The estimate uses the classic Fox formula: maximum heart rate = 220 minus your age. From that number, the widely accepted target zone is 50% to 85% of your maximum heart rate. Type in your age and the result card updates instantly, showing your max heart rate, your overall target range, and two sub-zones — the fat-burn zone (60%–70%) and the cardio zone (70%–85%).
How to Use
- Enter your age in years in the box. This drives the classic Fox maximum heart rate estimate.
- Optionally choose the Max HR Formula. The default Fox (220 − age) is the textbook formula taught in most certifications; switch to Tanaka (208 − 0.7 × age) if you are 40 or older, since Tanaka's 1994 regression fits adult populations slightly better and often predicts a more realistic Max HR.
- Optionally enter your Resting Heart Rate — count your pulse for a full minute first thing in the morning before getting out of bed, averaged over 3–5 days. The default of 70 bpm is a reasonable adult baseline; trained runners often sit at 40–55 bpm, which changes the Karvonen targets below.
- Read your Maximum Heart Rate — the theoretical fastest your heart can beat in one minute.
- Look at the Fox Target Heart Rate range (50%–85% of Max HR). This is the sweet spot for most aerobic exercise; staying inside it gives the best cardiovascular benefit without overreaching.
- Use the Fat Burn Zone (60%–70%) for longer, steadier sessions where your body relies more on fat for fuel.
- Use the Cardio Zone (70%–85%) for tempo runs, cycling intervals, and sustained effort that builds endurance and raises fitness faster.
- Compare the Karvonen Target range. This reserve-based formula (Karvonen, 1957) starts from your resting heart rate and adds a percentage of your heart-rate reserve (Max HR − Resting HR), which is more individualized than the plain Fox percentages.
- During a workout, check your pulse for 10 seconds and multiply by six, or glance at a chest strap or wrist device to confirm you are training in the intended zone.
A beginner should start near the 50% end of the range and build up over several weeks. A trained athlete may spend most of a session near the 85% end. The zones are guideposts, not rules carved in stone.
How the Formula Works
Your maximum heart rate (Max HR) is the upper limit of what your cardiovascular system can sustain during intense exercise. The Fox-and-Haskell estimate, published in 1971 and still taught in fitness certifications around the world, is simply:
Max HR = 220 − age
So a 30-year-old has an estimated Max HR of 220 − 30 = 190 beats per minute (bpm). The target heart rate zone recommended by the American Heart Association is then 50% to 85% of that maximum:
- Lower target (50%) = 190 × 0.50 = 95 bpm
- Upper target (85%) = 190 × 0.85 = 161.5 bpm
The calculator splits this range further: the fat-burn zone sits at 60%–70% of Max HR (about 114–133 bpm for a 30-year-old), and the cardio zone at 70%–85% (about 133–161.5 bpm). At lower intensities a larger share of burned fuel comes from fat; at higher intensities the body uses more glycogen and demands more oxygen, which is precisely what makes cardio training effective.
Why the Zones Matter
Training in the right zone keeps your workouts productive and safe. Pushing past 85% of Max HR for long periods can raise injury and exhaustion risk, especially if you are new to exercise or returning after a break. Staying between 50% and 70% lets you exercise longer and recover more easily. Roughly speaking:
- 50%–60% — warm-up and recovery; easy walking, gentle movement.
- 60%–70% — fat-burn / base endurance; brisk walking, casual cycling.
- 70%–80% — aerobic cardio; jogging, swimming, steady cycling.
- 80%–85% — tempo and threshold; faster intervals and harder efforts.
Keep in mind that the 220-minus-age rule is a population average with a margin of error of roughly ±10–12 bpm. Your true maximum can differ based on genetics, fitness level, medications, and altitude. More recent formulas such as Tanaka's (208 − 0.7 × age) are sometimes preferred for older adults, but the Fox formula remains the most widely recognized default.
Examples
Example 1 — A 30-year-old runner. Enter age 30. Max HR is 190 bpm. The target range is 95–162 bpm. An easy long run should keep the heart near 114–133 bpm (the fat-burn/base zone), while interval work can climb to 150–161 bpm in the upper cardio zone.
Example 2 — A 40-year-old starting exercise. Enter age 40. Max HR is 180 bpm, and the 50%–85% target range is 90–153 bpm. A beginner week might spend most sessions at 108–126 bpm (the lower end), building toward 126–153 bpm as fitness improves.
Example 3 — A 50-year-old cyclist. Enter age 50. Max HR is 170 bpm; the target range is 85–145 bpm. On a long, steady ride the cyclist holds about 102–119 bpm, reserving the 119–145 bpm cardio range for short climbs and efforts.
FAQ
What is a normal heart rate during exercise?
During moderate exercise your heart rate should fall somewhere between 50% and 70% of your maximum heart rate. For a 30-year-old with a max of 190 bpm, that is roughly 95–133 bpm. Vigorous exercise pushes into the 70%–85% range, about 133–161 bpm for the same person.
How do I calculate my maximum heart rate?
The standard estimate is 220 minus your age. If you are 35, your estimated maximum heart rate is 220 − 35 = 185 bpm. This is a guideline, not an exact measurement; your real maximum can vary by up to 10–12 bpm.
What is a good target heart rate zone?
For most healthy adults the American Heart Association recommends training between 50% and 85% of your maximum heart rate. Beginners and those returning after a break should start near the 50% end and gradually work up toward the 70%–85% cardio range.
How do I measure my heart rate manually?
Place two fingers on the side of your neck or on the wrist just below the thumb, count the beats for 10 seconds, then multiply by six. A chest strap or wrist-worn optical sensor gives a continuous reading and is more accurate for zone training.
Is the 220-minus-age formula accurate?
It is the most widely used estimate but it is a population average, not a precise individual value. It tends to overestimate maximum heart rate in some older adults. For a more personalized estimate, consider the Tanaka formula (208 − 0.7 × age) or, best of all, a graded exercise test supervised by a professional.
What heart rate is the fat-burn zone?
The fat-burn zone is typically 60%–70% of your maximum heart rate. At this lower intensity, a greater proportion of the fuel you burn comes from stored fat rather than glycogen, which is why steady, longer workouts in this zone are associated with fat-loss goals.
Disclaimer
This heart rate calculator is provided for informational purposes only and is not medical advice, diagnosis, or treatment. The 220-minus-age estimate and the resulting zones are population averages and should not be relied on for clinical decisions. Always consult a qualified healthcare provider before starting or changing an exercise program, especially if you have a heart condition, high blood pressure, diabetes, are pregnant, take heart-rate-affecting medication, or have been sedentary. Stop exercising and seek medical help immediately if you experience chest pain, dizziness, unusual shortness of breath, or irregular heartbeat.