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 Rate
5 kg 20 mL/hr
10 kg 40 mL/hr
15 kg 50 mL/hr
20 kg 60 mL/hr
25 kg 65 mL/hr
30 kg 70 mL/hr
35 kg 75 mL/hr
40 kg 80 mL/hr
45 kg 85 mL/hr
50 kg 90 mL/hr
55 kg 95 mL/hr
60 kg 100 mL/hr
65 kg 105 mL/hr
70 kg 110 mL/hr
75 kg 115 mL/hr
80 kg 120 mL/hr
85 kg 125 mL/hr
90 kg 130 mL/hr
95 kg 135 mL/hr
100 kg 140 mL/hr