Enter your age and your resting heart rate (bpm). The calculator estimates your maximum heart rate (HRmax = 220 − age) and then computes training zones based on heart-rate reserve (Karvonen). Everything runs locally in your browser.
About this target heart rate calculator
Training with heart rate can help you structure workouts and avoid going too easy—or too hard—by using “zones.” A target heart rate is a range of beats per minute (bpm) you aim to stay within during a session. Many plans describe zones such as easy endurance, moderate aerobic work, and harder intervals. This free calculator estimates your target ranges using the Karvonen method, which is based on heart-rate reserve (HRR). It uses two simple inputs: your age and your resting heart rate.
First, the tool estimates your maximum heart rate using a common approximation: HRmax = 220 − age. This value is not exact for everyone, but it provides a baseline. Then it computes heart-rate reserve: HRR = HRmax − resting HR. Karvonen zones are derived by adding back the resting heart rate: Target HR = resting HR + (HRR × intensity). In this calculator, “Moderate” corresponds to 50–70% of HRR, and “Intense” corresponds to 70–85% of HRR.
These ranges are useful for typical goals: moderate effort for longer aerobic sessions, and higher effort for tempo work or intervals. However, heart rate is influenced by hydration, stress, sleep, temperature, caffeine, medication, and measurement accuracy (watch vs chest strap). If your resting heart rate seems unusually high, or if you have symptoms (chest pain, dizziness, unusual shortness of breath), do not rely on a calculator—seek professional medical advice. This tool provides indicative estimates for general fitness planning.
Privacy is a key principle of Universe Tools: all calculations run 100% locally in your browser. Your inputs are not uploaded, stored, or shared.
Tip: measure resting heart rate in the morning before getting up for the most consistent value.
What is this calculator for?
This tool estimates target heart rate zones for training using the Karvonen method. You enter your age and resting heart rate, and it returns indicative ranges (in bpm) for moderate and intense effort.
Who is this useful for?
It’s useful for beginners and regular athletes who want a simple way to structure cardio sessions (walking, running, cycling, rowing, HIIT), compare effort levels, and avoid training “too hard” every day.
Concrete examples
- If you want an easy endurance session, use the moderate zone (50–70% HRR).
- If you’re doing tempo / intervals, use the intense zone (70–85% HRR) for work periods.
- If your heart rate is unusually high on a normal session, factors like heat, dehydration, stress, poor sleep can explain it.
Common mistakes
- Using an inaccurate resting HR (measure it calmly, ideally in the morning).
- Assuming the same zones apply every day (heart rate changes with fatigue and conditions).
- Thinking this is medical guidance (it’s an estimate for general fitness planning).
Alternatives and limitations
HRmax = 220 − age is a rough estimate. Real HRmax can be higher or lower. Devices can also differ (wrist optical sensors vs chest straps). If you have symptoms or medical concerns, use professional medical advice rather than a calculator.
Educational summary
Karvonen uses heart-rate reserve: HRR = HRmax − resting HR, then Target HR = resting HR + (HRR × intensity). The result is a practical bpm range to guide training intensity. Like the rest of Universe Tools, it runs locally and does not upload your data.