Bicarbonate Deficit Calculator

Estimates the HCO3 deficit to help diagnose metabolic acidosis and other conditions.

In the text below the tool there is information on the calculation and health implications of bicarbonate deficit.

HCO3 deficit is a sign of excessive organic and inorganic acids in the body, most often met in patients with metabolic acidosis.

The bicarbonate deficit calculator helps estimate the deficit that can then be used for diagnostic and treatment purposes.

The three variables required for the calculation are:

■ Patient weight – in either lbs or kg;

■ Measured bicarbonate in mEq/L;

■ Desired bicarbonate in mEq/L.

The formula used is:

Bicarbonate deficit = 0.4 x weight in kg x (desired HCO3 - measured HCO3)

Severe deficit is defined as measured HCO3

Patient weight
Measured Bicarbonate HCO3 (mEq/L)
Desired Bicarbonate HCO3 (mEq/L)
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


Variables considered

In order to estimate the bicarbonate deficit, the following variables are needed:

■ Patient weight – measurement taken in either pounds or kilograms;

■ Measured bicarbonate – test result in mEq/L;

■ Desired bicarbonate – arbitrary value in mEq/L, the bicarbonate deficit calculator has it set by default at 15 mEq/L.


Bicarbonate deficit formula

Bicarbonate deficit values are used by medical specialists in determining the causes of bicarbonate imbalance and taken into account when compensation treatment is planned.

The following formula determines it:

Bicarbonate deficit = 0.4 x weight in kg x (desired HCO3 - measured HCO3)

In order to put the formula in context, will take the case of a patient weighing 85 kg, with a measured HCO3 of 9 mEq/L (value considered as severe deficit), and a desired HCO3 of 16 mEq/L.

The bicarbonate deficit is 0.4 x 85 x (16 – 9), which is equal to 238 mEq/L.


HCO3 deficit implications

There are three sources of bicarbonate:

■ Renal generation caused by increased ammonium excretion;

■ Impaired hepatic metabolism of acid anions;

■ Exogenous administration of sodium bicarbonate in mineral acidosis.

Caused by the presence of excessive organic or inorganic acids, bicarbonate deficit is a symptom of metabolic acidosis along general malaise, weakness, nausea, abdominal pain, vomiting or acidic urine.

The body produces excessive acids because of:

■ Excessive acid intake;

■ Acid retention;

■ Loss of bases.

HCO3 deficit in metabolic acidosis is compensated by NaHCO3 (sodium bicarbonate).



1. Kurtz I. Acid-Base Case Studies. 2nd Ed. Trafford Publishing 2004; 68:150.

2. Sabatini S, Kurtzman NA. Bicarbonate therapy in severe metabolic acidosis. J Am Soc Nephrol. 2009; 20(4): 692-5.

Specialty: Deficiency

System: Digestive

Objective: Estimation

Type: Calculator

No. Of Variables: 3

Article By: Denise Nedea

Published On: March 16, 2017

Last Checked: March 16, 2017

Next Review: March 10, 2023