Calories Burned by Heart Rate
Enter your heart rate, age, weight, and workout duration to see how many calories you burned — with a full breakdown by training zone.
Calories burned if you had trained in each zone (same duration)
How calories burned by heart rate is calculated
This calculator uses a validated formula derived from research by Keytel et al. (2005) published in the Journal of Sports Sciences. It estimates calorie burn based on heart rate, age, sex, and weight — all variables that significantly affect energy expenditure during exercise.
The formula
For men: Calories/min = (−55.0969 + 0.6309 × HR + 0.1988 × weight(kg) + 0.2017 × age) / 4.184
For women: Calories/min = (−20.4022 + 0.4472 × HR − 0.1263 × weight(kg) + 0.074 × age) / 4.184
This is significantly more accurate than MET-based estimates because it accounts for individual physiological differences through heart rate — your body's real-time signal of exercise intensity.
Why heart rate predicts calorie burn
Heart rate reflects oxygen consumption, which directly correlates with energy expenditure. As your heart rate rises, your muscles demand more oxygen to produce ATP — and that oxygen demand is what burns calories. This is why a 140 bpm workout burns more calories per minute for a deconditioned person than a fit athlete: their hearts are working harder relative to their capacity.
What the number actually means: per minute, not per beat
Both formulas above produce calories per minute, not calories per heartbeat. That distinction causes a lot of confusion, because it is tempting to divide the result by your heart rate and treat the answer as "the cost of one beat." That division gives you an accounting average, not a physical measurement — and it is not what your heart itself is spending.
Your heart muscle uses roughly 1–2 joules per contraction, which works out to a small fraction of a calorie and totals only about 100–120 kcal across an entire day. That is the organ's own running cost, and it is roughly 7% of your basal metabolic rate. The 7 or 13 calories per minute this calculator reports during exercise are overwhelmingly being burned by your legs, glutes, and lungs — not by the heart. Heart rate is being used here as a proxy for how hard the rest of your body is working, which is why the formula also needs your weight, age, and sex to return a sensible number.
Practical takeaway: if you want a per-beat figure for curiosity, divide calories per minute by your bpm. If you want to know what your workout cost you, use the per-minute figure and multiply by duration. The second number is the one that matters for a calorie deficit.
The validity window: 90–150 bpm
The Keytel equations were derived from steady-state exercise testing, and they are most reliable when heart rate sits roughly between 90 and 150 bpm. Outside that band the output degrades in two specific ways, and knowing which direction it fails in is more useful than a generic accuracy warning:
- Below ~90 bpm: the regression can return implausibly low or even negative values, because resting metabolism dominates at that intensity and the equation was never fitted to it. Treat any very low reading as "not measurable here" rather than as a real number.
- Above ~150 bpm: heart rate begins to plateau while power output keeps climbing, so the formula progressively under-reports intense intervals and sprint work.
- Non-exercise elevation: caffeine, heat, illness, dehydration, and stress all raise heart rate without raising oxygen demand proportionally. The formula will read that as work and overestimate.
This is the single biggest reason a hard interval session and an easy steady run can produce estimates that feel backwards. For HIIT, total session calories are better approximated by treating the whole session as an average effort than by trusting a peak-heart-rate reading.
Roughly what to expect per minute
The table below shows approximate calories per minute from the formulas above, for a 70 kg (154 lb) 35-year-old, so you can sanity-check your own result before trusting it.
| Heart rate | Typical effort | Male (kcal/min) | Female (kcal/min) |
|---|---|---|---|
| 100 bpm | Brisk walk, easy warm-up | ~6.9 | ~4.3 |
| 120 bpm | Zone 2, conversational | ~9.9 | ~6.5 |
| 140 bpm | Steady run, tempo effort | ~13.0 | ~8.6 |
| 150 bpm | Upper limit of the valid range | ~14.5 | ~9.7 |
Note how much lower the female figures run at identical heart rates. That is the equation reflecting differences in average body composition and oxygen use, not an error — and it is exactly the individual variation that step-counting and generic MET tables miss.
Limitations to know
- Accuracy range: Formula-based estimates typically fall within ±15% of actual calorie burn. Lab testing (indirect calorimetry) is the only truly accurate method.
- Steady-state only: The formula is validated for steady-state cardio. It's less accurate for HIIT, weight training, or sport where heart rate fluctuates rapidly.
- Fitness level matters: Two people with the same heart rate may have different oxygen consumption levels depending on cardiovascular fitness — a factor this formula partially accounts for through the age variable.