Professional Clinical Energy Calculator

Indirect Calorimetry &
Metabolic Energy Profiler

Professional REE and energy-target estimation for qualified nutrition practice - Weir equation (full IC & VCO₂-only ICU mode), ICMR-NIN 2020 Indian adult adjustment, Henry Oxford, Mifflin-St Jeor, and Schofield Pediatric.

ICMR-NIN 2020 ESPEN ICU 2023 ASPEN 2024 Weir Equation Downloadable Report
Equations: Weir · Mifflin-St Jeor · Henry Oxford · Schofield · Cunningham · Katch-McArdle India: ICMR-NIN 2020 adult BMR adjustment ICU: ESPEN ICU 2023 · VCO₂-only mode · RQ validation Special: Pregnancy · Lactation · Geriatric ESPEN · Oncology IAPEN · Renal status
Patient Anthropometrics
Please select biological sex.
yrs
Enter age 0.1–120 years.
kg
Enter weight 1–300 kg.
cm
Enter height 30–250 cm.
Equation Selection

Indian adult adjustment: ICMR-NIN 2020 uses lower adult BMR estimates because international equations may overestimate BMR in Indian populations. The exact formula is shown in results.

ICMR India PAL values differ from WHO: sedentary = 1.40 (not 1.20).

Optional Body Composition Data

If LBM/FFM is known via BIA, DEXA, or skinfold, enable Cunningham/Katch-McArdle equations for superior accuracy. Otherwise leave blank - estimated LBM will be auto-computed via Boer formula.

kg

Direct entry - unlocks Cunningham & Katch-McArdle.

%

Auto-computes LBM if weight entered in Tab 1.

BMI & Weight Classification
Enter weight and height in Tab 1 to see BMI classification and adjusted body weight (AdjBW) for obese patients.
Measurement Mode
Tier 1 Full Indirect Calorimetry - Weir Equation

Enter both VO₂ and VCO₂ to activate the Abbreviated Weir equation. This is the reference method when performed under valid measurement conditions and overrides predictive equations. Add urinary nitrogen for complete Weir.

Formula Method
Abbrev. REE kcal/day = [(3.941 x VO2) + (1.106 x VCO2)] x 1440
Complete REE kcal/day = [(3.941 x VO2) + (1.106 x VCO2)] x 1440 - (2.17 x urinary nitrogen g/day)
Units VO2 and VCO2 are entered as L/min. Urinary nitrogen is entered as g/day and is not multiplied by 1440.
L/min

Physiological rest range: 0.10–0.40 L/min (ICU). Values outside warrant verification.

L/min

RQ = VCO₂ ÷ VO₂. Expected resting RQ: 0.70–1.00; review if outside this band; critical validity warning below 0.67 or above 1.30.

g/day

24-hr urine nitrogen. Abbreviated Weir used if omitted (<1–3% error).

Tier 2 VCO₂-Only - ICU Ventilator Mode

Use when ventilator capnometer data is available but full IC metabolic cart is unavailable. Assumes RQ=0.85 by default. Prefer this over predictive equations for mechanically ventilated patients when full IC is unavailable.

Formula Method
Default REE kcal/day = VCO2(mL/min) x 8.19, when assumed RQ = 0.85
Adjusted Estimated VO2 = VCO2 / assumed RQ; then REE = [(3.941 x VO2) + (1.106 x VCO2)] x 1440
mL/min

REE = VCO₂ × 8.19 (at RQ 0.85). Typical ICU adult: 100–300 mL/min. ±4–7.7% vs full IC.

ratio

Measured RQ requires both VO₂ and VCO₂. If both are available, use Full IC mode. Expected resting range: 0.70–1.00.

Tier 2b VO₂-Only Fallback

Use when only VO₂ is measurable (VCO₂ sensor unavailable or unreliable). REE estimated via assumed RQ. Accuracy lower than full IC - use as interim until VCO₂ data is available.

Formula Method
Step 1 Estimated VCO2 = VO2 x assumed RQ
Step 2 REE kcal/day = [(3.941 x VO2) + (1.106 x estimated VCO2)] x 1440
L/min

VO₂-only estimate: first estimate VCO₂ from assumed RQ, then run the abbreviated Weir equation. Lower confidence than full IC or ventilator-derived VCO₂.

ratio

Default 0.85 (mixed substrate). Adjust based on clinical context.

Tier 3 Predictive Mode - No Gas Measurement

No IC gas data entered. REE will be calculated using predictive equations based on demographics and body composition (Tab 1–2). Configure the equation and context settings there.

ESPEN ICU Nutrition Guideline 2023: predictive equations may be substantially inaccurate in critical illness. Consider IC measurement for ICU patients.

Measurement Quality & Protocol

Interface affects gas-exchange accuracy: ECMO and NIV carry highest error risk. Canopy is preferred for spontaneously breathing ICU patients.

min

ESPEN/ATS: ≥30 min recommended; minimum 20 min after achieving steady-state.

Failed calibration invalidates IC results - switch to VCO₂-only or predictive mode.

%

CV >10% = unstable steady-state. CV <5% = acceptable per ESPEN/ATS.

%

CV >10% triggers critical quality flag.

ratio

Room air = 0.21. IC invalid above FiO₂ 0.60 (dilution error).

Steady-state required for valid Weir result (ESPEN/ATS).

Any air leak makes VO₂/VCO₂ values unreliable - switch to VCO₂-only or predictive method.

Protocol Disturbance Checklist

Tick any disturbances that occurred during or within 30 min of measurement. Each checked item generates a clinical flag.

ICU Feeding Phase
Reproductive States
Oncology - IAPEN India
Geriatric - ESPEN Targets
Renal Protein Safety

Used only for protein guardrails. CKD without dialysis should not auto-prescribe high protein; dialysis and CRRT have separate targets.

Stress / Disease Factor

Applied to predicted REE only (Tier 3 equations). Automatically skipped for measured IC (Tier 1) and VCO₂-only (Tier 2) - multiplying a measured metabolic rate is clinically invalid. Use with caution even for predictive equations; direct IC measurement is always preferred in critical illness.

Clinical Priority Cascade

1
Full Indirect Calorimetry - Reference Method
VO₂ + VCO₂ via metabolic cart → Abbreviated Weir equation. Overrides predictive equations when valid quality conditions are documented. Optionally add 24-hr urinary nitrogen for complete Weir.
2
VCO₂-Only - ICU Ventilator Mode
Ventilator-derived VCO₂ (mL/min) → REE = VCO₂ × 8.19 at assumed RQ 0.85. Preferred over predictive equations in mechanically ventilated patients when full IC is unavailable.
3
Predictive Equations
Body composition equations (Cunningham/Katch-McArdle) if LBM known. Otherwise: ICMR-NIN 2020 for India, Henry Oxford for global diverse, Schofield for paediatric, Mifflin-St Jeor as general fallback.
4
Harris-Benedict - Comparison Only
Legacy 1984 revised formula shown in comparison table for reference. Not used as primary equation - systematically overestimates BMR, especially in obesity.
ICU nutrition: ESPEN practical and partially revised guideline: Clinical nutrition in the intensive care unit, 2023.
Critical care nutrition: ASPEN/SCCM critical care nutrition guidance.
Indian adult energy: ICMR-NIN 2020 nutrient requirements and adult BMR adjustment.
Metabolic measurement: AARC indirect calorimetry metabolic measurement clinical practice guidance.
Results will appear here

Complete patient demographics and press Calculate Metabolic Profile to generate REE, TDEE, protein prescription, equation comparison, and clinical advisory flags.

Metabolic Assessment Profile

-
Resting Energy Expenditure (REE)
- kcal/day
-
TDEE (with activity)
- kcal
PAL -
BMI
- kg/m²
-
Daily Energy Target
-kcal/day
Clinical Confidence
-
-
Formula, Inputs & Assumptions
Method -
Formula -
Inputs -
Assumptions -
Target phase -
Protein basis -
Protein Prescription
-
Min: - Recommended: - - Basis: -
Macro Preset
Protein
-
- kcal
Fat
-
- kcal
Carbs
-
- kcal
Measured REE vs Predictive Equations
ICMR-NIN 2020 Reference Bands India
- Enter demographics to see reference range
⚕ Clinical Use Notice Results support clinical decision-making but must be interpreted with patient condition, measurement validity, route of feeding, disease phase, and clinician judgement. ICMR-NIN 2020 · ESPEN ICU 2023 · ASPEN/SCCM critical care nutrition guidance.
Data & Privacy
All calculations run locally in your browser. No patient data is sent to any server. The downloadable report is generated on your device only.