Free calculate alveolar-arterial oxygen gradient (A-a gradient) to assess lung function. Get instant, accurate results with our easy-to-use calculator.
Blood Gas Values
Results
Enter blood gas values to calculate A-a gradient
About A-a Gradient
• Normal A-a gradient: <15 mmHg (room air) or <100 mmHg (100% O₂)
• Increased gradient suggests ventilation-perfusion mismatch or diffusion defect.