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Solve any one of pH/HCO₃⁻/PaCO₂ from the other two via pH = 6.1 + log10(HCO₃⁻/(0.03×PaCO₂)). Reports linear Henderson [H⁺] cross-check. Derived from Henderson 1908, Hasselbalch 1916, Siggaard-Andersen 1974, LITFL, StatPearls, Berend 2016. Not medical advice.
Execution
Fill in the form, run the tool, and review the result in one place.
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Tool usage guide
The Henderson-Hasselbalch calculator solves for pH, HCO₃⁻, or PaCO₂ when the other two values are provided. It also reports a linear Henderson [H⁺] cross-check and the calculated acid-base category. This tool is for equation-based reference and is not medical advice.
Background
A student is reviewing a standard acid-base example with HCO₃⁻ of 24 mmol/L and PaCO₂ of 40 mmHg.
Problem
Find the corresponding pH and verify the hydrogen ion estimate.
How to use
Enter HCO₃⁻ as 24, PaCO₂ as 40, and set Decimal Places to 2.
{"hco3":24,"paco2":40,"decimalPlaces":2}Outcome
The calculator solves pH as 7.40 and reports a linear Henderson [H⁺] cross-check of 40 nmol/L.
Background
An acid-base teaching case uses pH 7.20 and HCO₃⁻ of 20 mmol/L.
Problem
Determine the PaCO₂ implied by the Henderson-Hasselbalch equation.
How to use
Enter pH as 7.20, HCO₃⁻ as 20, and set Decimal Places to 2.
{"ph":7.2,"hco3":20,"decimalPlaces":2}Provide any two of pH, HCO₃⁻, and PaCO₂. The tool solves for the third.
Enter HCO₃⁻ in mmol/L and PaCO₂ in mmHg. Enter pH as a pH value such as 7.40.
Yes. When all three are entered, the calculator checks their Henderson-Hasselbalch consistency instead of solving for a missing value.
It is a linear Henderson cross-check calculated from [H⁺] = 24 × PaCO₂ / HCO₃⁻ and is reported in nmol/L.
No. The tool focuses on the Henderson-Hasselbalch equation and does not provide complete clinical interpretation or medical advice.
Outcome
The calculator solves PaCO₂ as approximately 52.96 mmHg, reports pH 7.20, and classifies the result as acidemia.