Oxygen-Hemoglobin Dissociation Curve Calculator:...

The Oxygen-Hemoglobin Dissociation Curve

Hemoglobin (Hgb) binds oxygen cooperatively — binding of the first O₂ increases affinity for subsequent O₂ molecules, creating a characteristic S-shaped (sigmoidal) oxyhemoglobin dissociation curve. The curve's position shifts with pH, CO₂, temperature, and 2,3-DPG, affecting oxygen delivery to tissues.

🩸 O₂-Hgb Dissociation Calculator

Free calculator for instant results.

Calculate Now →

📐 Formula

SaO₂ = PO₂ⁿ / (P₅₀ⁿ + PO₂ⁿ)

Hill equation: n = Hill coefficient ≈ 2.7 for human Hgb. P₅₀ = PO₂ at 50% saturation ≈ 26 mmHg (normal). SaO₂ = fractional saturation (0–1).

📝 Worked Example

At PO₂ = 100 mmHg (arterial blood, n=2.7, P₅₀=26):
SaO₂ = 100^2.7 / (26^2.7 + 100^2.7)
SaO₂ ≈ 97.5% (normal arterial saturation)

📝 How to Use

Enter PO₂Partial pressure of oxygen in mmHg or kPa.

Set ConditionsAdjust pH, temperature, CO₂, and 2,3-DPG to shift the curve.

View SaturationSee SaO₂ percentage at the specified PO₂.

Plot CurveVisualize the full S-shaped curve from PO₂ 0–150 mmHg.

❓ FAQ

What causes a right shift of the curve?

Bohr effect: increased CO₂, decreased pH, increased temperature, or increased 2,3-DPG all decrease Hgb-O₂ affinity (right shift), enhancing O₂ unloading to active tissues.

What is P₅₀?

The partial pressure of O₂ at which hemoglobin is 50% saturated. Normal P₅₀ ≈ 26 mmHg. Increased P₅₀ (right shift) means lower affinity; decreased (left shift) means higher affinity.