Maintenance fluids 421 rule calculator
Posted by dkwinter

"421 rule"

Rate of crystalloid per hour=

4mL/kg for first 10kg    (40)
+2mL/kg for next 10kg   (+20)
+1mL/kg for every next kg (+ (wt - 20 kg))

E.g. 110 mL/hr for a 70 kg pt

4-2-1 Maintenance Rate Calculator

Patient's weight in kg:
OR
Patient's weight in lbs:

Calculated maintenance infusion rate=


N.b.

Pediatric fluid bolus is 20mL/kg

Pediatric blood transfusion dose is 10cc/kg

Rates extrapolated for high mass (adults) may be inadequate, always titrate fluids based on patient needs and clinical context.

Avoid overloading patients with heart failure.

Avoid underhydrating patients who are dehydrated, in shock or burn victims.

Oliguria is <0.5 mL/kg/hour

See also:

 

4-2-1 Maintenance Rate Quick Lookup Table

Weight Weight Rate
11 lbs 5 kg 20 mL/hr
22 lbs 10 kg 40 mL/hr
33 lbs 15 kg 50 mL/hr
44 lbs 20 kg 60 mL/hr
55 lbs 25 kg 65 mL/hr
66 lbs 30 kg 70 mL/hr
77 lbs 35 kg 75 mL/hr
88 lbs 40 kg 80 mL/hr
99 lbs 45 kg 85 mL/hr
110 lbs 50 kg 90 mL/hr
121 lbs 55 kg 95 mL/hr
132 lbs 60 kg 100 mL/hr
143 lbs 65 kg 105 mL/hr
154 lbs 70 kg 110 mL/hr
165 lbs 75 kg 115 mL/hr
176 lbs 80 kg 120 mL/hr
187 lbs 85 kg 125 mL/hr
198 lbs 90 kg 130 mL/hr
209 lbs 95 kg 135 mL/hr
220 lbs 100 kg 140 mL/hr