Calculator
Example Data Table
| Mass | Duration | Input mode | Input | RER | Gross energy | Average power |
|---|---|---|---|---|---|---|
| 70 kg | 30 min | MET | 3.5 MET | 0.85 | 125.08 kcal | 290.74 W |
| 80 kg | 45 min | MET | 8.0 MET | 0.92 | 498.80 kcal | 772.96 W |
| 60 kg | 20 min | MET | 10.0 MET | 1.00 | 211.97 kcal | 739.08 W |
Formula Used
MET to relative oxygen uptake:
VO₂ relative = MET × 3.5
Relative oxygen uptake to absolute oxygen uptake:
VO₂ absolute = VO₂ relative × body mass ÷ 1000
Energy equivalent from RER:
kcal per liter O₂ = 3.815 + 1.232 × RER
Energy rate:
kcal per minute = VO₂ absolute × energy equivalent
Total energy:
Total kcal = kcal per minute × duration
Physics power conversion:
Average watts = total kcal × 4184 ÷ duration seconds
Body surface area:
BSA = √((height in cm × mass in kg) ÷ 3600)
Heart rate equations:
Male kcal/min = [-55.0969 + 0.6309HR + 0.1988W + 0.2017A] ÷ 4.184
Female kcal/min = [-20.4022 + 0.4472HR - 0.1263W + 0.074A] ÷ 4.184
How to Use This Calculator
- Select the input method that matches your available data.
- Enter body mass and exercise duration.
- Add RER when oxygen exchange data is available.
- Use MET for activity tables or simple estimates.
- Use VO₂ modes for laboratory or exercise test data.
- Use heart rate mode only when oxygen data is absent.
- Press the calculate button to view results above the form.
- Use the CSV or PDF button to save your report.
Metabolic Energy in Physics
Metabolic Energy in Physics
Metabolic energy expenditure links human motion with heat, work, and oxygen use. In physics terms, the body is an engine. It converts chemical energy into mechanical output and thermal loss. This calculator estimates that energy with several practical entry points. You can start with MET values, relative oxygen uptake, absolute oxygen uptake, or heart rate. Each route gives the same style of report.
What the Numbers Show
The main result is total energy in kilocalories and kilojoules. The calculator also reports average power in watts. This is useful because energy alone does not show intensity. A short hard effort can use less total energy than a long walk. Yet it may require far higher power. Oxygen use is also shown. It helps connect breathing data with energy release. The RER value adjusts the energy gained from each liter of oxygen. Lower values suggest more fat use. Higher values suggest more carbohydrate use.
Advanced Interpretation
Net energy removes estimated resting demand. This makes activity cost easier to read. Gross energy includes rest and movement together. Both views are useful. Laboratory reports often need gross totals. Training analysis often needs net totals. Power per body surface area helps compare people with different body sizes. It is still an estimate. Heat stress, efficiency, posture, and equipment can change true energy cost.
Good Input Practice
Choose the mode that matches your data. Use MET values for known activities. Use VO₂ values for exercise tests or gas analysis. Use heart rate when oxygen data is not available. Keep duration in minutes. Enter body mass in kilograms. Use a realistic RER between 0.70 and 1.00. Check units before submitting. Small unit errors can create large energy errors.
Limits of Estimation
These equations are educational tools. They are not medical decisions. Individual efficiency can differ. Fitness level, temperature, illness, and calibration affect results. Heart rate formulas are indirect. They should be treated as rough estimates. For research, measured oxygen and carbon dioxide data is stronger. For class work, the formulas show how physical energy, oxygen flow, and average power connect in one clear calculation.
Use repeated trials when possible. Average the results. This reduces random error and improves comparisons across sessions and workloads.
FAQs
What is metabolic energy expenditure?
It is the energy used by the body during rest or activity. This calculator estimates it from oxygen uptake, MET level, or heart rate data.
Why is this listed under physics?
The tool converts chemical energy into kilojoules and watts. Those are physics units for energy and power.
What does MET mean?
MET means metabolic equivalent. One MET is commonly treated as 3.5 ml of oxygen per kilogram per minute.
What is RER?
RER means respiratory exchange ratio. It compares carbon dioxide output with oxygen uptake and adjusts the energy value of oxygen.
Which input mode is best?
Measured VO₂ is usually strongest. MET is useful for activity estimates. Heart rate mode is helpful when lab data is unavailable.
What is gross energy?
Gross energy includes resting metabolism and activity cost together. It shows total estimated energy during the full duration.
What is net energy?
Net energy subtracts resting energy from gross energy. It estimates the extra cost caused by the activity.
Can this replace a lab test?
No. It is an educational estimator. Calibrated gas analysis is better for clinical, athletic, or research decisions.