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
Select the sex coefficient required by the equation.

Recorded only to select the sex-specific equation coefficient; document gender identity separately in the clinical record where relevant.

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 lean body mass (LBM/FFM) has been measured by a valid method - DEXA or quality-controlled BIA - Cunningham and Katch-McArdle may improve the relevance of predicted REE. A Boer estimate may be shown for reference, but it does not activate or silently replace a measured-LBM equation.

kg

Direct entry - unlocks Cunningham & Katch-McArdle.

%

Auto-computes LBM if weight entered in Patient Details.


BMI & Weight Classification
Enter weight and height in Patient Details to see BMI classification and adjusted body weight (AdjBW) for obese patients.

Weight basis Weight Basis for Dosing

Clinical dosing weight differs by scenario. Actual weight suits most patients; ideal/adjusted are used in obesity; dry (euvolemic) weight is preferred where fluid overload, oedema, ascites, or dialysis inflate measured weight. The chosen basis drives the protein prescription.

Actual (ABW)
Ideal (IBW · Devine)
Adjusted (AdjBW)
Dry / euvolemic
Post-dialysis
kg

Post-dialysis / true euvolemic weight. Recommended dosing basis for dialysis, oedema, ascites, or fluid overload.

“Auto” follows guideline logic (e.g. IBW for ICU obesity). Override when fluid status or body habitus warrants a different basis. Applies to protein; energy equations retain their guideline weight.

Choose Measurement Pathway

Most users start with Predictive — no gas data needed. Choose Full IC, VCO₂-only, or VO₂-only only if you have metabolic-cart or ventilator gas-exchange values.

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 a full IC metabolic cart is not. The REE multiplier is computed live from the assumed RQ - the familiar ×8.19 corresponds to RQ ≈ 0.86, not 0.85. Prefer this over predictive equations for mechanically ventilated patients when full IC is unavailable.

Formula Method
Multiplier REE kcal/day = VCO2(mL/min) x multiplier(RQ); multiplier(RQ) = ((3.941 / RQ) + 1.106) x 1.44
RQ reference RQ 0.80 → ×8.69 · RQ 0.85 → ×8.27 · RQ 0.86 → ×8.19 · RQ 0.90 → ×7.90. The commonly cited ×8.19 assumes RQ ≈ 0.86.
Live Enter an assumed RQ to preview the multiplier.
mL/min

Enter in mL/min (typical ICU adult 100–300). This method is generally more accurate than predictive equations but less accurate than full IC; the individual error cannot be assumed from a population average.

ratio

Default 0.86 → multiplier ≈ ×8.19 (canonical). At RQ 0.85 the multiplier is ≈ ×8.27. Measured RQ requires both VO₂ and VCO₂ — use Full IC mode if both are available. 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 (Patient Details & Body Composition tabs). 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.


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.

Hospital Assessment Workspace

Add ward-round context, weight trend, current intake delivery, and the hospital protocol assumptions that must appear in the final report.


Weight Trend & Fluid Status

Optional hospital assessment fields. Dry weight is never estimated from oedema or ascites; enter only a clinically verified dry/euvolemic weight in Body Composition.

kg
kg
kg
kg
kg

Current Delivery vs Prescription

Enter only documented intake delivered in the same 24-hour period. Propofol and IV dextrose contribute energy but not protein.

Sourcekcal/dayProtein g/day

Hospital / Clinical Protocol assumptions shown in report
kg

Selecting “Local protocol” records the assumption; it does not silently replace formula coefficients. Use clinician overrides where provided and document the local rule.

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 × multiplier(RQ). The commonly cited ×8.19 assumes RQ ≈ 0.86 (at RQ 0.85 it is ≈8.27). 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
Revised 1984 formula shown for historical comparison only. Its accuracy varies substantially across body sizes and clinical populations, so it is not used as the primary method in this calculator.
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.
Live Clinical Snapshot Fill in the inputs — this updates live, then press Calculate.
Enter biological sex, age, weight and height to begin.

Live Clinical Snapshot

-
Resting Energy Expenditure (REE)
- kcal/day
-
Estimated daily energy before clinical adjustment
- kcal
PAL -
BMI
- kg/m²
-
Daily Energy Target
-kcal/day
After feeding phase, disease status & clinician judgement.
Measurement validity
-
-
    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.
    View Full Clinical Report