Total Body Water Calculator
Estimate total body water and fluid compartments using adult or paediatric equations.
Version 1.0.0
Estimation method
Sex
Total body water
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L
Intracellular fluid
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L
Extracellular fluid
—
L
Plasma volume
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L
Estimates may be inaccurate when body composition differs substantially from the populations represented by the selected method.
No clinical values are intentionally saved by this control.
Equations
60% male / 50% female method
TBW (L) = 0.60 × weight (kg) [male]; TBW (L) = 0.50 × weight (kg) [female]The unrounded estimate is rounded to the nearest whole litre before fluid compartments are derived.
Watson equation
TBW (L) = 2.447 − (0.09156 × age [years]) + (0.1074 × height [cm]) + (0.3362 × weight [kg]) [male]; TBW (L) = −2.097 + (0.1069 × height [cm]) + (0.2466 × weight [kg]) [female]The female equation does not use age. The unrounded estimate is rounded to the nearest whole litre before fluid compartments are derived.
Hume–Weyers equation
TBW (L) = (0.194786 × height [cm]) + (0.296785 × weight [kg]) − 14.012934 [male]; TBW (L) = (0.34454 × height [cm]) + (0.183809 × weight [kg]) − 35.270121 [female]Age is not used by this equation. The unrounded estimate is rounded to the nearest whole litre before fluid compartments are derived.
Mellits–Cheek equation — male
TBW (L) = −1.927 + (0.465 × weight [kg]) + (0.045 × height [cm]) when height < 132.7 cm; TBW (L) = −21.993 + (0.406 × weight [kg]) + (0.209 × height [cm]) when height ≥ 132.7 cmPaediatric method. Age is used for input-range validation but not in the equation. The unrounded estimate is rounded to the nearest whole litre before fluid compartments are derived.
Mellits–Cheek equation — female
TBW (L) = 0.076 + (0.507 × weight [kg]) + (0.013 × height [cm]) when height < 110.8 cm; TBW (L) = −10.313 + (0.252 × weight [kg]) + (0.154 × height [cm]) when height ≥ 110.8 cmPaediatric method. Age is used for input-range validation but not in the equation. The unrounded estimate is rounded to the nearest whole litre before fluid compartments are derived.
Estimated fluid compartments
ICF (L) = 0.55 × rounded TBW; ECF (L) = 0.45 × rounded TBW; plasma volume (L) = rounded TBW ÷ 15Variables: TBW = total body water; ICF = intracellular fluid; ECF = extracellular fluid. Each compartment is displayed to one decimal place.
References
- International Commission on Radiological Protection. Report of the Task Group on Reference Man. ICRP Publication 23. Oxford: Pergamon Press; 1975.
- Watson PE, Watson ID, Batt RD. Total body water volumes for adult males and females estimated from simple anthropometric measurements. Am J Clin Nutr. 1980;33(1):27-39. PMID: 6986753 DOI: 10.1093/ajcn/33.1.27
- Hume R, Weyers E. Relationship between total body water and surface area in normal and obese subjects. J Clin Pathol. 1971;24(3):234-238. PMID: 5573438 DOI: 10.1136/jcp.24.3.234
- Mellits ED, Cheek DB. The assessment of body water and fatness from infancy to adulthood. Monogr Soc Res Child Dev. 1970;35(7):12-26. PMID: 5508372