Arterial Blood Gas Analyzer

ABG Calculator & ABG Analyzer

Enter pH, PaCO₂, HCO₃⁻, and PaO₂ to quickly interpret arterial blood gas results, identify acid-base disorders, assess compensation, and classify oxygenation.

Real-value analyzer

Enter ABG values

Use pH, PaCO₂, HCO₃⁻, and PaO₂ values from the same arterial sample. Reference ranges are shown as entry hints.

Calculated in your browser

*PaO₂ interpretation varies with FiO₂, age, altitude, and the clinical setting.

Use values from the same arterial sample and clinical moment.
Built by a Registered Respiratory TherapistValues are processed locally in your browserClinical decision-support, not a diagnosis

Normal ABG values

Arterial blood gas reference ranges at a glance

These commonly used adult ranges provide an interpretation framework, but laboratory references and clinical context can vary.

pH
7.35–7.45

Overall arterial acid–base direction

PaCO₂
35–45 mmHg

Respiratory contribution to acid–base balance

HCO₃⁻
22–29 mEq/L

Metabolic contribution to acid–base balance

PaO₂
80–100 mmHg*

Arterial oxygen tension; context dependent

*PaO₂ is especially dependent on age, FiO₂, altitude, and the clinical setting.

PulmTools for iPhone

Turn ABG practice into measurable progress.

Keep the bedside tools you use most close at hand, then build confidence with progress tracking, focused review, and personalized learning.

Track progress

Accuracy, points, and streaks.

Review smarter

Focused repetition for missed concepts.

Stay consistent

Reminders and personalized queues.

Coming soon to the App StoreFree core tools with optional Premium learning features.
PulmTools iPhone app showing the clinical home screen and ABGenius progress tracking dashboard

ABG interpretation workflow

How to use this ABG analyzer

Use this ABG calculator when you already have arterial blood gas values and want a fast, organized interpretation. Enter pH, PaCO₂, HCO₃⁻, and PaO₂, then review the likely acid-base pattern and oxygenation category together.

  1. Start with pH to decide whether the blood gas shows acidemia, alkalemia, or a normal-range pH.
  2. Compare PaCO₂ and HCO₃⁻ to determine whether the primary disorder is respiratory, metabolic, or mixed. When the pattern suggests metabolic acidosis, verify whether the PaCO₂ response is appropriate with Winter’s Formula instead of assuming every low PaCO₂ is a primary respiratory alkalosis.
  3. Use PaO₂ to classify oxygenation and decide whether hypoxemia is present.

For deeper study, read the ABG Analysis Guide or practice repeated cases with ABGenius.

Related tools & guides

Keep building acid-base confidence

ABG Analysis GuideStep-by-step ABG interpretation framework.ABGeniusPractice realistic arterial blood gas cases.VBG AnalyzerInterpret venous blood gas values fast.A–a Gradient CalculatorEvaluate causes of hypoxemia.P/F Ratio ExplainedUnderstand oxygenation and ARDS severity.Winter’s FormulaCheck whether respiratory compensation is appropriate in metabolic acidosis.
Clinical methodology

Acid–base interpretation with oxygenation kept in context

The ABG calculator evaluates arterial pH first, compares PaCO₂ and HCO₃⁻ to identify a likely primary acid–base process, checks whether the other value moves in a compensatory direction, and reports the PaO₂ band separately.

  • Directional compensation is not presented as proof that compensation is quantitatively appropriate.
  • PaO₂ is interpreted with an explicit reminder to consider FiO₂, age, altitude, and baseline physiology.

Common ABG questions

ABG calculator FAQ

Quick answers for students, respiratory therapists, nurses, and clinicians reviewing arterial blood gas interpretation.

What is an ABG calculator?

An ABG calculator organizes arterial pH, PaCO₂, HCO₃⁻, and PaO₂ values to identify a likely acid-base pattern, describe compensation direction, and place oxygenation in clinical context.

What is a normal ABG?

Normal ABG values are pH 7.35–7.45, PaCO₂ 35–45 mmHg, HCO₃⁻ 22–29 mEq/L, and PaO₂ 80–100 mmHg.

How do you interpret an ABG?

Start with pH, then compare PaCO₂ and HCO₃⁻ to identify the primary disorder, assess compensation, and finish by evaluating oxygenation.

What does PaO₂ indicate?

PaO₂ reflects arterial oxygenation and helps classify hypoxemia as mild, moderate, or severe.

What is compensation in ABGs?

Compensation is the body’s attempt to bring pH back toward normal through respiratory or metabolic adjustment.