# Bicarbonate Deficit Calculator

URL: https://speedycalculator.com/calculators/health/bicarbonate-deficit/
Last updated: 2026-10-30

> The bicarbonate deficit calculator estimates how much bicarbonate would be needed to raise the serum bicarbonate to a target in metabolic acidosis, from body weight and the distribution volume of bicarbonate.

## Inputs

- Weight (kg, lb, st, g)
- Measured bicarbonate (mEq/L)
- Target bicarbonate (mEq/L)
- Distribution factor

## Results

- Bicarbonate deficit
- Half the deficit (usual initial amount)
- 8.4% sodium bicarbonate, mL (1 mEq/mL)

## Formula

```
HCO₃⁻ deficit (mEq) = 0.5 × weight (kg) × (target HCO₃⁻ − measured HCO₃⁻)
(distribution factor 0.4–0.7, higher in severe acidosis)
```

## Explanation

Bicarbonate therapy is controversial and reserved for specific situations such as severe acidosis with pH below about 7.1, hyperkalaemia or some poisonings. Usually only half the calculated deficit is given at first, with repeat blood gases.

### How to use the Bicarbonate Deficit Calculator

- **Weight**
- **Measured bicarbonate**
- **Target bicarbonate**
- **Distribution factor**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter weight, measured and target bicarbonate and the distribution factor.

### Inputs explained

FieldWhat to enterWeightUnits: kg, lb, st, gMeasured bicarbonateIn mEq/LTarget bicarbonateIn mEq/LDistribution factorA number

### What each result means

- **Bicarbonate deficit** = [Distribution factor]×[Weight]×([Target bicarbonate] - [Measured bicarbonate])
- **Half the deficit (usual initial amount)** = [Bicarbonate deficit]÷2
- **8.4% sodium bicarbonate, mL (1 mEq/mL)** = [Bicarbonate deficit]÷2

### Example values

How the main result changes when **Weight** changes and everything else stays at the example values above:

Weight (kg)Bicarbonate deficit (mEq)3514052.52107028087.5350105420140560
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Weight: 70 kg; Measured bicarbonate: 10 mEq/L; Target bicarbonate: 18 mEq/L; Distribution factor: 0.5.

Results — **Bicarbonate deficit = 280 mEq**; Half the deficit (usual initial amount) = 140 mEq; 8.4% sodium bicarbonate, mL (1 mEq/mL) = 140 mL.

## Key terms

- **Distribution factor**: Fraction of body weight that bicarbonate distributes into.

## FAQ

**When is bicarbonate given?**
Mainly for severe acidosis (pH < 7.1), hyperkalaemia, some poisonings and bicarbonate losses.

**Why give only half?**
Ongoing losses and generation make the deficit uncertain; repeated checks prevent overcorrection.

**What are the risks?**
Sodium and fluid overload, low potassium and calcium, and overshoot alkalosis.


## Sources

- [Kraut JA, Madias NE. Treatment of acute metabolic acidosis: a pathophysiologic approach. Nat Rev Nephrol, 2012](https://pubmed.ncbi.nlm.nih.gov/22945490/)