Transparent calculator · Energy 1.2
Maintenance & Energy Needs Calculator
Estimate resting energy and a deliberately broad maintenance range, with an optional 14-day reality check.
Purpose
What this tool is for
Use this when you need a transparent starting range for everyday energy intake—not a target-date diet prescription.
Audience
Who it is for
Generally healthy adults aged 19–78 who train recreationally and understand that an equation is only a starting estimate.
Input glossary
What each field means
| Input | Unit or choice | Why it matters |
|---|---|---|
| Age | years | The equation subtracts five kilocalories for each year of age. |
| Weight | kg or lb | Converted to kilograms before it enters the equation. |
| Height | cm or ft/in | Converted to centimetres before calculation. |
| Equation branch | female / male | Mifflin–St Jeor published two constants. This is an equation parameter, not a complete description of sex or gender. |
| Activity band | light / moderate / vigorous | Selects a broad FAO physical-activity-level band; it is not a wearable measurement. |
| Optional log | 14 weights + 14 intake values | Compares two seven-day weight averages and reports logged intake only when the trend is broadly stable. |
Method · Energy 1.2
The formula or decision logic
Resting energy estimate = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + equation constant. The constant is +5 for the published male branch and −161 for the published female branch.
The estimate is multiplied by a broad physical-activity-level range: light 1.40–1.69, moderate 1.70–1.99 or vigorous 2.00–2.40.
For the optional log, the mean of days 8–14 is compared with days 1–7. A trend within ±0.25% per week is labelled “broadly stable”; that band is a Nutrinaut planning heuristic, not a clinical threshold.
References support the method or context; they do not validate an individual result. See the sources.
Worked example
Example, not a recommendation: Sam’s starting range
- Sam uses the male equation branch, is 30 years old, weighs 70 kg and is 175 cm tall.
- 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 1,648.75 kcal/day resting estimate.
- Using the light PAL band: 1,648.75 × 1.40–1.69 = 2,308–2,786 kcal/day.
Interactive calculator
Estimate your starting range
Nothing you enter is sent to our server. Calculation happens in this browser.
Reproducible checks · 10 October 2026
Check the calculation, not just the claim
These are synthetic arithmetic and input-validation cases—not user records, experiments or proof that an estimate fits an individual. Actual values are generated from the same calculator functions for this release and included in the initial page HTML. Expected values are fixed reference fixtures.
Energy estimates round resting energy to the nearest kcal and composite ranges to the nearest 10 kcal. Label nutrients round to 0.1 g or mg, energy and reference percentages to whole numbers. Blank optional nutrients stay unknown, not zero.
Metric reference
Pass30 years; 70 kg; 175 cm; male branch; light PAL
- Expected
- 1649 kcal/day resting; 2310–2790 kcal/day composite
- Actual
- 1649 kcal/day resting; 2310–2790 kcal/day composite
Only the activity assumption changes
PassSame inputs; moderate PAL
- Expected
- 2800–3280 kcal/day
- Actual
- 2800–3280 kcal/day
Imperial conversion
PassUI-rounded equivalent: 154.3 lb; 5 ft + 8.9 in; otherwise metric reference
- Expected
- 1649 kcal/day resting; 2310–2790 kcal/day composite
- Actual
- 1649 kcal/day resting; 2310–2790 kcal/day composite
Complete stable demonstration log
Pass14 weights of 70 kg; 14 intakes of 2450 kcal
- Expected
- 0 %/week; 2450 kcal/day logged intake
- Actual
- 0 %/week; 2450 kcal/day logged intake
Invalid weight rejected
Pass0 kg
- Expected
- Weight must be between 35 and 250.
- Actual
- Weight must be between 35 and 250.
Invalid weight rejected
Pass-1 kg
- Expected
- Weight must be between 35 and 250.
- Actual
- Weight must be between 35 and 250.
Invalid weight rejected
Pass251 kg
- Expected
- Weight must be between 35 and 250.
- Actual
- Weight must be between 35 and 250.
Invalid weight rejected
PassMissing / non-finite kg
- Expected
- Weight must be between 35 and 250.
- Actual
- Weight must be between 35 and 250.
Incomplete calibration rejected
Pass13 weights; 14 intakes
- Expected
- Calibration needs 14 daily weights and 14 daily intake values.
- Actual
- Calibration needs 14 daily weights and 14 daily intake values.
Validation boundaries are software scope limits, not health thresholds. A passing fixture checks arithmetic and display behaviour, not clinical validity. Method sources and limitations
Limitations
What the result cannot tell you
- Equations can differ materially from measured expenditure.
- Activity bands are coarse and day-to-day needs vary.
- Fluid shifts, menstrual-cycle changes, travel, illness and inconsistent food logging can obscure a two-week trend.
- The tool does not calculate a deficit, surplus, “safe minimum,” weight-loss rate or target date.
Questions specific to this tool
Frequently asked questions
Is maintenance the same every day?
No. Movement, training, recovery and normal measurement error vary. The range is more honest than a single fixed number.
Why does the tool ask for an equation branch?
The published Mifflin–St Jeor equation contains different male and female constants. It did not provide another validated parameterisation.
Is 14 days always enough?
No. Two weeks is a practical observation window, not proof of true energy expenditure. Noisy data or a clear trend means gathering more data is sensible.
Should I add exercise calories again?
Not automatically. The activity multiplier is intended to represent total daily activity. Adding the same exercise again can double-count it.
Why can weight rise without an intake change?
Hydration, glycogen, food mass, sodium, menstrual-cycle changes and measurement timing can all alter scale weight without implying a matching fat change.
Evidence and official references
Sources
A new predictive equation for resting energy expenditure in healthy individuals
American Journal of Clinical Nutrition / PubMed · 1990
Supports: Resting-energy equationHuman energy requirements: physical activity level
FAO/WHO/UNU · 2004
Supports: PAL categories and uncertaintyFound a numerical or source issue? Send a correction with the page URL.
Apply the method
Why two energy estimates can both look plausible
A worked sensitivity check showing how the activity choice changes the output.
Read Eugene Blago’s field noteRead the latest field note
Check the minutes before trusting workout calories
Elapsed time and moving time are not interchangeable. Check the duration and source before adding exercise calories to a daily estimate.
Read Eugene Blago’s field note