One main difference between adult and pediatric nursing is that children come in all different shapes and sizes. We get infants all the way up to 26 year olds! Because of this, the majority of pediatric nursing is based off of the patient’s weight in kilograms. Knowing how to do these calculations is imperative because kids are extremely sensitive to being given too much fluid or having too much taken out. I developed this quick cheat sheet of common calculations to help keep our pediatric patients safe!


Weight (lbs) ÷ 2.2= weight in kilograms

  • How much does a patient who weighs 75lbs weigh in kg?
    • 75lbs ÷ 2.2 = 34kg

√ height (cm) x weight (kg) ÷ 3600

  • What is the BSA of a 34kg patient who is 122cm?
    • 34kg X 122cm= 4148
    • 4148 ÷ 3600= 1.15
    • √1.15= 1.07
  1. Pt weighing 3.5-10kg, daily fluid requirement is 100mL/kg
  2. Pt weighing 11-20kg, daily fluid requirement is 1000mL + 50mL/kg for every kg over 10
  3. Pt weighing >20kg, daily fluid requirement is 1500mL + 20mL/kg for every kg over 20
  4. Max of 2400mL/D
  • What should the maintenance fluids be for a patient weighing 6kg, 13kg, 45kg, and 100kg?
    • Patient 6kg: 6kg X 100mL= 600mL/dayPatient 13kg: 1000mL + 50(3)= 1150mL/day
    • Patient 45kg: 1500mL +20(25)=2000mL/day
    • Patient 100kg: 1500mL +20(80)= 2400mL max/day


  • What is the safe Packed Red Blood Cell volume for a patient weighing 15kg?
    • 15kg X 10= 150mL
    • 15kg X 20= 300mL
    • The safe volume of PRBCs to transfuse for this patient is 150-300mL

Should not exceed 1-5% of total blood volume in one day

-Newborns 85mL/kg total blood volume

-1-12 months 75mL/kg total blood volume

-1-3 year olds 70mL/kg total blood volume

-3 years + 65mL/kg total blood volume

  • How much blood can be drawn on a newborn weighing 5kg?
    • 5kg X 85mL= 425mL total blood volume
    • 0.01 X 2275mL=4.25mL
    • 0.05 X 2275mL= 21.25mL
    • Blood draw should  not exceed 21.25 mL/day

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