Source: https://guthlabs.ai/docs/instruments/metabolic-equivalent-met-activity-energy-calculator/mechanism/

instrument mechanism / verified-clean

# Metabolic Equivalent (MET) / Activity Energy Calculator mechanism

The inspectable method record for Metabolic Equivalent (MET) / Activity Energy Calculator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The core formula is standard for gross energy expenditure, but the instrument needs an explicit duration unit, a versioned MET lookup convention, input constraints, and an honest gross-versus-net label. The fourth test vector is deliberately corrected in its working: 8.0 × 3.5 × 75 / 200 = 10.5 kcal/min, so 1 hour produces 630 kcal.

- The formula kcal/min = MET × 3.5 × weight(kg) / 200 is the standard population-average estimate for gross energy expenditure, assuming 1 MET = 3.5 mL O2/kg/min and approximately 5 kcal/L O2.

- The specification does not state whether the result is gross calories or net/active calories. Net expenditure is commonly estimated as (MET - 1) × 3.5 × weight(kg) / 200, so the output label must explicitly say gross or net.

- The duration unit is unspecified. Because the formula produces kcal/min, duration must be explicitly supplied or converted to minutes.

- The activity-MET lookup and activity-name mapping are unspecified; the instrument needs a defined Compendium table version and behavior for activities absent from the table.

## Units and conventions

- MET is dimensionless and represents the activity's gross metabolic rate relative to resting metabolism.

- Weight is body mass in kilograms.

- The formula output is kilocalories per minute.

- Duration is converted to minutes before multiplication; one hour equals 60 minutes.

- The 3.5 mL O2/kg/min MET convention and approximately 5 kcal per liter of oxygen convention are assumed.

- Expected outputs below are gross kcal, not net active kcal.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "activity": "Walking at 3.0 mph",
    "met": 3.5,
    "weight_kg": 70,
    "duration_min": 30
  },
  "expected_outputs": {
    "kcal_per_min": 4.2875,
    "total_kcal": 128.625
  },
  "reference_data": {
    "activity": "Walking, 3.0 mph",
    "met": 3.5,
    "source_convention": "widely tabulated standard value; Compendium of Physical Activities, 2011 update (Ainsworth et al.)"
  },
  "working": "MET × 3.5 × weight / 200 = 3.5 × 3.5 × 70 / 200. First, 3.5 × 3.5 = 12.25. Then 12.25 × 70 = 857.5. Then 857.5 / 200 = 4.2875 kcal/min. Total = 4.2875 × 30 = 128.625 kcal."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The extreme-magnitude vector causes floating-point overflow, and the duration field has an unresolved unit ambiguity that can change the result from 183.75 kcal to 11025 kcal for the same numeric input.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/metabolic-equivalent-met-activity-energy-calculator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/metabolic-equivalent-met-activity-energy-calculator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/metabolic-equivalent-met-activity-energy-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`