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The IVIG dose calculator computes:

  • The immunoglobulin dose based on the ideal body weight of a patient; or
  • The Rh(D) immune globulin dose needed to prevent hemolytic disease of the fetus and newborn in case of a maternal hemorrhage. 💉

Our IVIG weight-based dosing takes into account the patient's BMI by using the adjusted body weight calculation formula if necessary.

❗ The RhIG/IVIG dose calculator cannot be used as a substitute for clinical knowledge and/or consultation with a medical specialist. Always consult your doctor. Be sure to double-check your calculations.

What is an IVIG infusion?

An IVIG infusion, or an intravenous immune globulin treatment, contains important proteins, known as antibodies, that help your body identify and fight infections. These antibodies are one of the most important parts of your immune system. 🔬

Immunoglobulins "latch" into foreign particles called antigenes. This way, they can tag a certain bacteria or an infected cell, marking it for destruction.

Why do we need IVIG infusions?

IVIGs are used in a variety of diseases, including:

  • Primary immunodeficiency (when your body cannot defend itself against common infections);
  • Autoimmune diseases, such as Guillain–Barré syndrome (when your body attacks its own cells and organs);
  • In people with leukemia, or after a bone marrow transplant;
  • Certain cases of HIV/AIDS; and
  • Kawasaki disease.

How to calculate IVIG dose based on weight?

It's really simple!

  1. Compute the ideal weight of the patient.
    If the patient's BMI is less than 30, you may use the Devine formula. ⚖️


    Ideal weight = 45.5 + 2.3 × (Height − 1.524)/0.0254


    Ideal weight = 50.0 + 2.3 × (Height − 1.524)/0.0254


    • Weight — Given in kilograms, and must exceed 20 kg (44.1 lb); and

    • Height — Given in meters, and must exceed 1.5m (4.9 ft).

  2. Finally, let's calculate the IVIG dose

    IVIG dose = Dosing × Ideal weight


    • IVIG dose — Given in grams (g);
    • Dosing — Given in g/kg; and
    • Ideal weight — Given in kilograms (kg).

    ❗If the actual weight is lower than the ideal weight, use the actual weight instead of the ideal weight.

💡 Take a look at our ideal weight calculator to discover all the other equations that can be used to compute the ideal mass of a patient.

How to calculate IVIG dosing in obese patients?

Let's do this!

If the patient's BMI is greater than or equal to 30, we should use their adjusted body weight, also called the dosing body weight.

  1. Compute the ideal weight.


    Ideal weight = 45.5 + 2.3 × (Height − 1.524)/0.0254


    Ideal weight = 50.0 + 2.3 × (Height − 1.524)/0.0254

  2. Find the dosing body weight.

    Dosing body weight = Ideal weight + 0.5 × (Actual weight − Ideal weight)

    All weights are given in kilograms.

  3. ...and compute the IVIG dose! 🏋️

    IVIG dose = Dosing × Dosing weight


    • IVIG dose — Given in grams (g),
    • Dosing — Given in g/kg,
    • Ideal weight — Given in kilograms (kg).

As you can see, calculating the dose of immunoglobulin requires a bit of effort. Thankfully, you can always use Omni's IVIG dose calculator!

What are Rh(D) immune globulins?

Rh(D) immunoglobulins are antibodies that target red blood cells that present the D antigen. We know it may all seem pretty complicated, but we'll explain everything step by step.

  • Our red blood cells, called erythrocytes, transport oxygen via our blood.
  • All erythrocytes carry proteins that serve as their "IDs", which allow them to be recognized as their own by our immune system.
  • These proteins are inherited, and are responsible for differences in blood types among different people. 🆎🅰️🅾️🅱️ To learn more about blood types, visit Omni blood type calculator.

Antigen D is one of these inheritable proteins; if you remember, your blood type is usually written as AB+, 0-, A+, B+, 0+. We mark the presence of antigen D as +, and its absence as -. It's just as easy as that!

Why do we need RhIG?

RhIGs are especially important in preventing the hemolytic disease of the fetus and newborn. This disease may happen if the mother's erythrocytes do not contain the D antigen (possible mother's blood types: A-, B-, AB-, 0-) and the fetus does contain them (possible fetus blood types: A+, B+, AB+, 0+).

As a result of these blood type mismatches, the mother's immune system may attack the fetus's blood cells because it recognizes the D antigen as foreign material and so tries to destroy it.

As a result of this process, the fetal blood cells are broken up, resulting in fetal anemia and edema, which can be lethal.

But, if the mother's antibodies against the D antigen are to blame for the disease, why do we administer them ourselves? 🤔

We administer the ready-to-go antibodies so that they'll bind to the D antigen before the mother's immune system can, and so hide it from attack. As a result, the mother's body won't be able to recognize the antigen, preventing it from triggering an immune response that could potentially hurt the baby.

How to calculate immunoglobulin dose for maternal/fetal hemorrhage?

Physicians give Rh(D) immunoglobulins to Rh(D) negative mothers to prevent the newborn from suffering from hemolytic disease. Let's follow a few simple steps to obtain the RhIG dose needed:

  1. Find out the blood volume of the mother. If you don't want to calculate it, you may use our blood volume calculator.

  2. Find out the percentage of fetal cells in the mother's bloodstream. You'll need flow cytometry or the Kleihauer-Betke methodology.

  3. Use the equation featured in the IVIG calculator:

    RhIG dose = Fetal cells % × Maternal blood/30 + 1


    • RhIG dose — Number of 30 mL vials of 300 µg RhIG (1500 IU); and
    • Maternal blood — In milliliters (mL)

Of course, our IVIG dose calculator can perform all these calculations for you in the blink of an eye!


Which weight should we use to compute IVIG dosing?

We should generally use the ideal weight formula if we want to compute the proper immunoglobulin dose. However, there are a few exceptions:

  • If the patient's actual weight is lower than the ideal weight (actual<ideal), we need to use the actual weight instead.

  • IVIG dosing in obese patients (BMI ≥ 30) should be calculated using the adjusted body weight calculation formula (the dosing weight).

How to calculate maternal blood volume?

You may calculate the mother's blood volume using the Nadler’s formula:

Maternal blood (mL) = (356.1 × Height³) + (33.08 × Weight) + 183.3


  • Mother's height — Given in meters (m); and
  • Mother's weight — Given in kilograms (kg).

Psst!. You may also use one of the dedicated Omni calculators! 🕹️

Łucja Zaborowska, MD, PhD candidate
Type of calculation
General dosing
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