A–a Gradient (Alveolar–arterial Oxygen Gradient) Calculator
Use this A–a gradient calculator to evaluate the cause of hypoxemia. It is helpful for clinicians, respiratory therapists, and students assessing ventilation-perfusion mismatch, shunting, and diffusion impairment.
Learn the underlying concept in our A–a Gradient guide, compare oxygenation severity in the P/F Ratio guide, or review full arterial interpretation in the ABG Interpretation Guide.
An elevated A–a gradient indicates a problem with oxygen transfer from the alveoli to the bloodstream. It helps distinguish the cause of hypoxemia, whether it is due to ventilation-perfusion mismatch, diffusion defect, or shunting.
Pair this tool with the ABG Analyzer for full blood gas interpretation, review the A–a Gradient guide, or compare oxygenation severity with the P/F Ratio article.