To calculate a target heart rate for weight loss, use the Karvonen formula: Target HR = (HRmax − resting HR) × intensity + resting HR, where HRmax = 220 − age and intensity is written as a decimal. The method estimates maximum heart rate from age, finds the gap between that estimate and resting heart rate, then applies your chosen training intensity to that reserve. The Target Heart Rate Calculator applies this approach to three inputs: age in years, resting heart rate in bpm, and a target intensity percentage. It shows a single calculated training bpm for the intensity you select and a broader training zone spanning 50% to 85% of heart-rate reserve. For weight-loss cardio, this provides a practical pace for moderate or vigorous aerobic work; it does not guarantee a particular rate of fat loss or weight change. The method can be more personal than simply taking a percentage of maximum heart rate because resting heart rate reflects current fitness. However, 220 − age is still a population estimate, so use the output as a starting guide rather than an exact ceiling.
What the target means for weight-loss cardio
A target heart rate is the estimated pace for a selected effort level, not the highest rate you should ever reach. The calculator’s wider 50%–85% zone is based on heart-rate reserve rather than the entire estimated maximum. Resting heart rate is added back after the selected percentage is applied.
Two people of the same age can receive different targets because their resting heart rates differ. A lower resting rate creates a larger heart-rate reserve, producing a higher calculated target at the same intensity. For weight loss, there is no universal target bpm: use the number to pace cardio, then adjust it according to your effort, fitness, and health context rather than forcing the monitor reading.
Calculate your target from three inputs
- Enter your age in years. The calculator estimates maximum heart rate with the widely used Fox equation: HRmax = 220 − age.
- Enter your resting heart rate in bpm. Ideally, measure it first thing in the morning before getting out of bed so it represents your resting baseline.
- Enter your target intensity as a percentage, such as 70. Read the calculated target heart rate in bpm along with the broader 50%–85% training zone. The results update instantly.
Enter 70 when the field asks for 70%; the formula uses 0.70 during the calculation. The single target answers your chosen intensity, while the wider zone shows where that effort sits within the calculator’s moderate-to-vigorous reference range.
Why resting heart rate changes the result
The Karvonen method, also called the heart-rate reserve method, separates your estimated maximum from the rate you normally have at rest. It consists of three linked calculations:
- Estimated maximum: HRmax = 220 − age.
- Heart-rate reserve: HRR = HRmax − resting HR.
- Target heart rate: Target HR = HRR × intensity decimal + resting HR.
Worked example: For a 30-year-old with a resting heart rate of 60 bpm, HRmax = 220 − 30 = 190 bpm. The reserve is 190 − 60 = 130 bpm. At 70% intensity, the target is (130 × 0.70) + 60 = 151 bpm.
This is why adding resting heart rate back matters. The selected intensity applies only to the reserve between resting and estimated maximum heart rates. Someone with a lower resting rate has more of that reserve to work with, so the same age and intensity can lead to a different target for each person.
Match intensity to the kind of effort
Intensity in the Karvonen method is a percentage of heart-rate reserve, not a percentage of maximum heart rate. Use the following guide to relate the calculator’s percentages to common training demands:
| Intensity of heart-rate reserve | General effort | Typical activity or purpose |
|---|---|---|
| Below 50% | Base or recovery effort | Recovery work or a very easy aerobic base |
| About 50%–70% | Moderate aerobic effort | Brisk walking or easy cycling |
| About 70%–85% | Vigorous effort | Running or interval work |
| Above 85% | Very hard, approaching anaerobic effort | An intensity that can be difficult to sustain |
The calculator displays the 50%–85% zone so you can compare moderate and vigorous work. Around 70% is a transition point, so the talk test can help distinguish the two. Beginners generally start near the lower end and build upward over several weeks instead of beginning with the most demanding pace.
Use a target that can progress over weeks
Use the calculated bpm as a pacing reference for cardio rather than a pass-or-fail score. A heart-rate zone can show whether an effort resembles your intended intensity, but it does not measure the calories used during a session or the change on the scale. Those parts of a weight-loss plan must be assessed separately.
As fitness improves, your resting heart rate may gradually fall and the same effort may begin to feel easier. You can enter the updated resting rate in the calculator and calculate a fresh target rather than forcing your workout to match an old number. Progressing over several weeks also gives you time to become familiar with how moderate and vigorous efforts feel.
Cross-check the monitor with effort
A heart-rate number is easier to interpret when you also notice how the exercise feels. The talk test provides a simple field check:
- At moderate intensity, you should be able to hold a conversation.
- At vigorous intensity, you may be able to manage only short phrases.
- Without a monitor, rate perceived effort on a 1-to-10 scale and use it alongside your calculated zone.
Perceived effort can help when illness, heat, or fatigue shifts your response away from your usual average. If the talk test, perceived effort, and monitor reading do not agree, treat that mismatch as a reason to reassess the session instead of pushing harder to match the number.
Keep the estimate accurate and safe
Measure resting heart rate by counting your pulse for a full 60 seconds after waking and before getting out of bed. Repeat on several mornings and use the average. Caffeine, stress, dehydration, poor sleep, and illness can all raise the reading, so an occasional elevated value may not represent your usual baseline.
The calculator’s methodology treats 220 − age as a population average that may differ from an individual’s true maximum by roughly 10–12 bpm. Its result is therefore a starting estimate, not a precise personal maximum or medical limit.
All calculations are performed locally in your browser, and nothing you type is uploaded. This is a general fitness tool, not medical advice. If you have a heart condition, take medication that affects heart rate, such as beta blockers, or are new to exercise, talk with a doctor before using the calculated targets.