Arterial Blood Gas (ABG) Calculator
Read an arterial blood gas at a glance, from pH, carbon dioxide, and bicarbonate.
Awaiting Data
Enter your details and tap Calculate to see your results appear here.
Your result appears here.
What it measures
An arterial blood gas shows how well your lungs and kidneys keep blood in balance. Three numbers carry most of the meaning: pH for acidity, PaCO2 for the lungs, and bicarbonate for the kidneys. Read together, they reveal acidosis or alkalosis and its likely source.
This tool names the primary disturbance and checks for compensation. Treat it as a learning aid only. For heart and lung context, see our Healthy Heart Rate guide.
How to use this calculator
- Read pH, PaCO2, and HCO3 from the lab report.
- Enter each value in its field.
- Tap Calculate for the interpretation.
- Confirm any clinical decision with a professional.
The formula used
- pH
- Blood acidity.
- PaCO2
- Carbon dioxide, the lung side.
- HCO3
- Bicarbonate, the kidney side.
Understanding Your Results
Tips to Improve
- Always read pH first to set the direction.
- Match PaCO2 and HCO3 to find the source.
- Look for compensation in the other value.
- Correlate with the patient, never the number alone.
Frequently Asked Questions
A pH under 7.35 signals acidosis. The cause may be respiratory or metabolic.
The second system shifts the same way to pull pH back toward normal.
No. It is an educational aid. Clinical judgement and full data are essential.
Scientific References
- Berend, K., et al. (2014). Physiological approach to acid base balance. New England Journal of Medicine, 371, 1434–1445.
- Hennessey, I. A., & Japp, A. G. (2015). Arterial Blood Gases Made Easy.