GIR Calculator (Glucose Infusion Rate)
Enter the patient weight, dextrose concentration, and IV infusion rate to calculate the Glucose Infusion Rate (GIR) in mg/kg/min. You can add up to three separate dextrose solutions running simultaneously - common when a neonate has both a peripheral dextrose drip and a central parenteral nutrition line. Enable reverse-solve to find the IV rate needed to hit a target GIR instead.
What is the Glucose Infusion Rate (GIR)?
The Glucose Infusion Rate (GIR) is the amount of glucose delivered intravenously per unit of time, expressed in milligrams of glucose per kilogram of body weight per minute (mg/kg/min). It is the standard metric used in neonatal and pediatric intensive care to ensure that a patient receiving IV dextrose is getting enough glucose to avoid hypoglycemia and catabolism, but not so much that they develop hyperglycemia, osmotic diuresis, or hepatic lipogenesis. The GIR is calculated from three pieces of information: the concentration of the dextrose solution (as a percentage, which equals g/dL numerically), the infusion rate in mL/hr set on the IV pump, and the patient weight in kg.
The GIR formula and how it works
The formula is: GIR (mg/kg/min) = [rate (mL/hr) x concentration (g/dL) x 1000 mg/g] / [weight (kg) x 60 min/hr x 100 mL/dL]. The 1000 converts grams to milligrams; the 60 converts hours to minutes; and the 100 converts dL to mL to cancel the volume units. Simplified, this becomes GIR = (rate x concentration x 10) / (weight x 60). For a 1.5 kg neonate receiving D10W at 3.5 mL/hr: GIR = (3.5 x 10 x 1000) / (1.5 x 60 x 100) = 35,000 / 9,000 = 3.89 mg/kg/min - slightly below the standard term-infant maintenance target of 4-6 mg/kg/min. When multiple dextrose solutions run simultaneously (for example, a peripheral D10W drip and a central parenteral nutrition bag containing D12.5W), the GIR from each line is calculated separately and the results are summed.
Neonatal GIR targets and clinical interpretation
For term neonates, most protocols target a GIR of 4-6 mg/kg/min to maintain blood glucose above 40-50 mg/dL in the first hours and above 50 mg/dL thereafter. Preterm and very-low-birth-weight neonates typically need 5-8 mg/kg/min because their liver glycogen stores are smaller and gluconeogenesis is immature. GIR below 4 mg/kg/min leaves many neonates prone to hypoglycemia; above 8 mg/kg/min in a term infant, or above 10-12 mg/kg/min in any neonate, raises the risk of hyperglycemia and the lipogenic effects of excess glucose. In neonates with persistent hyperinsulinism, diazoxide- or octreotide-refractory cases may require GIR above 15 mg/kg/min while awaiting surgery, but this demands intensive glucose monitoring. GIR is always interpreted alongside actual blood glucose values: a neonate with a GIR of 6 mg/kg/min who is hypoglycemic needs the rate increased; one who is euglycemic or hyperglycemic at 4 mg/kg/min may need it held or reduced.
Reverse-solve: finding the IV rate for a target GIR
This calculator includes a reverse-solve mode that answers a common clinical question: "At what rate do I need to run my D10W to achieve a GIR of 6 mg/kg/min in this 1.2 kg neonate?" Rearranging the GIR formula gives rate (mL/hr) = GIR x weight (kg) x 60 x 100 / (concentration x 1000). This is equivalent to rate = GIR x weight x 6 / concentration. For a 1.2 kg neonate, target GIR 6, D10W: rate = 6 x 1.2 x 6 / 10 = 4.32 mL/hr. Switch to reverse-solve mode, enter the patient weight, concentration, and target GIR, and the calculator provides the required pump rate directly. Note that the reverse-solve applies to solution 1 only; if multiple lines are running, calculate the contribution from the other lines first and enter their GIRs as an adjustment.
GIR target ranges by patient type
| Patient type | Target GIR (mg/kg/min) | Clinical note |
|---|---|---|
| Term neonate | 4-6 | Standard maintenance to prevent hypoglycemia |
| Preterm neonate | 5-8 | Higher metabolic demand; some centers target up to 10 |
| Infant (under 1 year) | 4-8 | Titrate to blood glucose 50-110 mg/dL |
| Child (1-10 years) | 3-5 | Lower glucose demand per kg than neonates |
| Adolescent / adult | 2-4 | Parenteral nutrition glucose component |
| Hypoglycemia treatment | 6-8 (or higher) | Titrate up until euglycemia is achieved |
| Maximum safe limit | Less than 12-14 | Higher rates risk hyperglycemia and fatty liver |
Standard glucose infusion rate targets. Actual targets should be individualized based on blood glucose monitoring and clinical status.
Frequently asked questions
What is a normal GIR for a newborn?
For a full-term newborn, the standard maintenance GIR is 4-6 mg/kg/min. Preterm and very-low-birth-weight neonates often need 5-8 mg/kg/min because of their limited glycogen stores and immature gluconeogenesis. These are starting targets; the actual rate is titrated based on frequent blood glucose measurements.
Why is GIR expressed in mg/kg/min instead of mL/hr?
Expressing the rate per kilogram per minute normalizes glucose delivery to the patient's body weight and makes it independent of the dextrose concentration used. A rate of 5 mL/hr of D10W and 2.5 mL/hr of D20W both deliver the same amount of glucose to the same patient, but the pump settings look completely different. GIR in mg/kg/min captures the actual glucose load, making it the standard unit for neonatal glucose management and for comparing patients of different sizes.
Can I add more than one dextrose solution?
Yes. This calculator supports up to three simultaneous dextrose solutions - toggle on "Add second dextrose solution" and "Add third dextrose solution" to enter their concentrations and rates. The calculator computes the GIR from each line and sums them. This is important for neonates receiving both a peripheral dextrose drip and a central parenteral nutrition solution, or for patients where a dextrose "piggyback" is added temporarily.
What happens if GIR is too high?
GIR above 12-14 mg/kg/min delivers more glucose than most neonates can metabolize by oxidation. The excess is converted to fat in the liver (hepatic lipogenesis), which can cause or worsen hepatic steatosis during prolonged parenteral nutrition. Acutely, a high GIR drives hyperglycemia, which causes osmotic diuresis, dehydration, and in preterm neonates may be associated with worse outcomes. Monitor blood glucose frequently and titrate the rate down if hyperglycemia develops.
How do I use the reverse-solve mode?
Select "Find IV rate for target GIR" in the Mode field. Enter the patient weight and the concentration of the dextrose solution you will use. Then enter your desired GIR target (e.g. 6 mg/kg/min). The calculator returns the pump rate in mL/hr for that solution. If other dextrose solutions are already running, you would need to subtract their GIR contribution from your target before using reverse-solve for the remaining line.
Does GIR apply to adults or only to neonates?
GIR is most commonly used in neonatal and pediatric intensive care, where precise glucose management is critical and patients are too small for volumetric targets to be intuitive. In adult critical care and parenteral nutrition, glucose delivery is usually prescribed in g/day rather than mg/kg/min, but the concept is the same. This calculator can be used for any weight if GIR is the required metric.
Is dextrose percentage the same as g/dL?
Yes, numerically they are equal. A "10% dextrose" solution (written D10W) contains 10 g of dextrose per 100 mL, which is 10 g/dL. The GIR formula uses g/dL, so you can enter the percentage directly without any conversion. D5W = 5 g/dL, D12.5W = 12.5 g/dL, D25W = 25 g/dL, and so on.
Sources
- Hay WW Jr. Strategies for feeding the preterm infant. Neonatology. 2008;94(4):245-254.
- Rozance PJ, Wolfsdorf JI. Hypoglycemia in the Newborn. Pediatric Clinics of North America. 2019;66(2):333-342.
- Kalhan S, Parimi P. Gluconeogenesis in the fetus and neonate. Seminars in Perinatology. 2000;24(2):94-106.