Arterial Blood pH Calculator
Calculate arterial blood pH using the Henderson-Hasselbalch equation for acid-base analysis
Calculate Arterial Blood pH
Medical Professional Use Only
This calculator is for healthcare professionals performing arterial blood gas analysis. Results require clinical correlation and should not replace professional medical judgment.
Normal: 22-28 mEq/L
Normal: 35-45 mmHg (4.7-6.0 kPa)
Arterial Blood pH Results
Enter values to calculate pH
Henderson-Hasselbalch Equation
Example Calculation
Normal ABG Values
Patient Values:
• HCO₃⁻: 24 mEq/L
• PaCO₂: 40 mmHg
• Expected pH: ~7.40
Henderson-Hasselbalch
pH = 6.1 + log₁₀[24 / (0.0308 x 40)]
pH = 6.1 + log₁₀[24 / 1.232]
pH = 6.1 + log₁₀[19.48]
pH = 6.1 + 1.29 = 7.39
ABG Parameters
Arterial pH
Measure of blood acidity/alkalinity
PaCO₂
Respiratory component
Bicarbonate
Metabolic component
Normal Ranges
Understanding Arterial Blood pH
What is Arterial Blood Gas (ABG)?
Arterial blood gas analysis measures the amounts of arterial gases and determines arterial pH. The test assesses the body's acid-base balance and the efficiency of gas exchange in the lungs, providing critical information for diagnosing and managing respiratory and metabolic disorders.
Clinical Applications
- •Assess respiratory function and ventilation
- •Evaluate acid-base balance disorders
- •Monitor critically ill patients
- •Guide mechanical ventilation settings
Henderson-Hasselbalch Equation
pH = 6.1 + log₁₀[HCO₃⁻ / (0.0308 x PaCO₂)]
Where:
- 6.1 = pKa of carbonic acid system
- HCO₃⁻ = bicarbonate concentration (mEq/L)
- 0.0308 = solubility constant for CO₂
- PaCO₂ = arterial CO₂ partial pressure (mmHg)
Clinical Note: The equation shows that pH depends on the ratio of HCO₃⁻ (metabolic component) to PaCO₂ (respiratory component), not their absolute values.
Acid-Base Disorders
Acidosis (pH < 7.35)
Metabolic Acidosis:
- Diabetic ketoacidosis
- Kidney failure
- Lactic acidosis
Respiratory Acidosis:
- COPD
- Respiratory failure
- Hypoventilation
Alkalosis (pH > 7.45)
Metabolic Alkalosis:
- Vomiting
- Diuretic use
- Hyperaldosteronism
Respiratory Alkalosis:
- Hyperventilation
- Anxiety
- High altitude