Bicarbonate Deficit Calculator

Created by Joanna Michałowska, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Last updated: Feb 15, 2022

The bicarbonate deficit calculator estimates bicarbonate deficit to help diagnose metabolic acidosis and other medical conditions. Read the article below to find out what bicarbonate is, how to calculate bicarbonate deficit, and what are the medical complications associated with it.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice.

Physiological role of bicarbonate

Bicarbonate can be presented using two chemical formulas - HCO₃ and CO₂. Carbon dioxide is the main by-product of metabolism that is circulated in the blood, and bicarbonate is a major form of it.

Below you will find the key information regarding bicarbonate:

  • It is a negatively charged ion which is excreted and reabsorbed by the kidneys.
  • It is also transported to the lungs and then exhaled as carbon dioxide.
  • It helps to maintain acid-base balance in the blood.
  • It works with the other electrolytes, including sodium, potassium, and chloride, to maintain electrical neutrality at the cellular level.
  • Knowing bicarbonate level might be useful in the investigation of acid-base status.

Bicarb deficit can occur in:

Bicarb deficit - symptoms

Low bicarbonate level in the blood is a sign of metabolic acidosis, which might be associated with the following symptoms:

  • Long and deep breaths
  • Fast heartbeat
  • Headache, confusion, and weakness
  • Tiredness
  • Vomiting and/or nausea
  • Loss of appetite.

How to calculate bicarbonate deficit - bicarbonate deficit formula

Bicarbonate deficit formula can be presented as follows:

bicarb deficit = 0.5 * weight * (desired bicarb – bicarb level)


  • bicarb deficit - bicarbonate deficit

  • weight - is expressed in kilograms (don't worry if you are using different units - our bicarbonate deficit calculator will convert them for you)

  • desired bicarb - desired bicarbonate level expressed in mmol/L, the reference values for bicarbonate ranges from 22 to 29 mmol/L

  • bicarb level - actual bicarbonate level expressed in mmol/L

Depending on the result, treatment with sodium bicarbonate can be introduced. However, the dosage of the medication depends on the patient's health status and the cause of bicarbonate deficit. Bicarbonate replacement therapy remains controversial in some patients, e.g., with severe metabolic acidosis.

Reference for bicarbonate deficit formula: Lim S. Metabolic Acidosis. Acta Med Indones-Indones J Intern Med. 2007.

Bicarbonate deficit calculator - calculate bicarbonate deficit

Let's use an example to show how bicarbonate deficit calculator works.

  1. First of all, you need to enter the patient's weight. Let's assume that it is 72 kilograms (159 lbs).

  2. You need to enter the patient's bicarbonate level. Let's assume that it is 19 mmol/L.

  3. Choose desired bicarbonate level. The default value in our bicarbonate deficit calculator is set to be 24 mmol/L, but feel free to change it.

The calculations look as following:

bicarb deficit = 0.5 * weight * (desired bicarb – bicarb level)

bicarb deficit = 0.5 * 72 kg * (24 mmol/L – 19 mmol/L)

bicarb deficit = 0.5 * 72 * 5

bicarb deficit = 180 mmol/L

Bicarbonate deficit of this patient equals 180 mmol/L.

Joanna Michałowska, PhD candidate
Patient's weight
Actual bicarbonate level
Desired bicarbonate level
Bicarbonate deficit
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