Maintenance Fluid Calculations

Determine maintenance IV fluid rates


The maintenance fluid calculator was derived in 1957 by Holliday and Segar for the pediatric population but has persisted in use for both adults and pediatric patients to date. It was derived based on estimated energy expenditure amongst sicker children admitted to hospitals. The formula is based off of the assumption that hospitalized patients have greater energy expenditure and determines fluid requirements based on weight alone (a proxy for energy expenditure in a non-linear relationship).

Other maintenance fluid calculators have been derived and employed, however the "4-2-1" rule remains the most widely used for adults and pediatric populations secondary to its ease of calculation

Variable & Associated Points
Maintenance Fluid Rate is calculated based on weight.

  • 4 mL / kg / hour for the first 10kg of body mass
  • 2 mL / kg / hour for the second 10kg of body mass (11kg - 20kg)
  • 1 mL / kg / hour for any kilogram of body mass above 20kg (> 20kg)


Holliday MA and Segar WE.

Pediatrics 1957, 19 (5): 823-32

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