Calculator Inputs
Use general allometric constants or customize them for your species dataset.
Example data table
These sample rows show how body mass, coefficients, and temperature settings can change the final estimate.
| Animal group | Mass | a | b | Temperature | Q10 | Activity | Estimated kcal/day |
|---|---|---|---|---|---|---|---|
| Mammal | 5.0 kg | 70 | 0.75 | 37 °C | 1.0 | 1.2 | 281.98 |
| Bird | 0.8 kg | 129 | 0.72 | 40 °C | 1.0 | 1.3 | 148.22 |
| Reptile | 2.2 kg | 10 | 0.80 | 30 °C | 2.0 | 1.1 | 44.15 |
| Fish | 1.5 kg | 8 | 0.82 | 18 °C | 1.8 | 1.4 | 12.19 |
Formula used
The calculator uses a generalized allometric equation. Basal energy is estimated from body mass, then optional temperature and activity adjustments are applied.
Basal metabolic rate: BMR = a × Mb
Temperature correction: Temperature Factor = Q10(T − Tref) / 10
Adjusted metabolic rate: MR = BMR × Temperature Factor × Activity Factor
- a is the intercept coefficient for the animal group.
- M is body mass in kilograms.
- b is the mass-scaling exponent.
- Q10 estimates how rate changes with a 10 °C shift.
- Activity factor increases energy demand above resting conditions.
How to use this calculator
- Select the animal group that best matches your study subject.
- Enter body mass and choose the correct mass unit.
- Keep the preset coefficient and exponent or replace them with species-specific values.
- Enter an activity factor to move from basal to field conditions.
- Enable temperature correction if your animal is temperature-sensitive or habitat temperature varies.
- Press the calculate button to show results above the form, beneath the header.
- Use the CSV or PDF buttons to export the current results for reporting.
Frequently asked questions
1. What does this calculator estimate?
It estimates daily metabolic energy from body mass, group-specific constants, temperature response, and activity level. The result is a planning estimate, not a clinical measurement.
2. Why do different animal groups use different coefficients?
Different taxa have different baseline physiology. Birds often show higher resting energy demand than reptiles, while ectotherms generally stay lower at comparable body mass.
3. When should I apply the temperature correction?
Use it when metabolic rate changes strongly with body or habitat temperature. It is especially useful for reptiles, amphibians, fish, and many invertebrates.
4. What is a reasonable activity factor?
A factor near 1.0 suits resting conditions. Values around 1.2 to 1.5 fit light activity, while more demanding behavior may justify higher multipliers.
5. Are these results species-specific?
Not by default. The presets are broad biological averages. Replace the coefficient and exponent with published species values for more accurate research use.
6. Why is the result shown in several units?
Energy budgeting often needs more than one unit. Watts help compare power demand, while kilocalories and megajoules are useful for feeding and ecological planning.
7. Can I export the output?
Yes. Use the export buttons after calculation to save a CSV summary or a PDF snapshot of the main results for records or sharing.