Pressure (blood gas) kPa → mmHg
Convert pressure (blood gas) from kPa to mmHg
Sources last checked: 2026-11-03
Pressure (blood gas) kPa → mmHg
Convert pressure (blood gas) from kPa to mmHg
Converts units only; reference ranges depend on the laboratory, the assay and the patient.
What is the Pressure (blood gas) kPa → mmHg?
This converter changes partial pressures from kPa — used for blood gases in the UK, Scandinavia and the Netherlands — into mmHg, used in Germany, Austria, Turkey and the USA. It divides by 0.1333 (equivalent to multiplying by about 7.50), based on 1 mmHg = 133.322 Pa (NIST SP 811).
When to use it
- Interpreting a blood gas report or guideline in kPa in an mmHg setting
- Applying P/F-ratio thresholds defined with PaO₂ in mmHg to a kPa result
- Reading UK or Scandinavian literature in respiratory and critical care
When not to use it
- Pressures in cmH₂O or mbar (ventilation, intracranial monitoring in some devices) — these need different factors
- Gas fractions (FiO₂) in % or as a decimal — they are not pressures
How it is calculated
mmHg = kPa ÷ 0.1333 (≈ kPa × 7.50)
Clinical pearls and limitations
- Converts units only; reference ranges depend on the laboratory, the assay and the patient.
- 1 kPa ≈ 7.50 mmHg.
- Convert PaO₂ before calculating a P/F ratio against mmHg-based thresholds, or convert the threshold — never mix.
- In the A–a gradient, all pressures (barometric, water vapour, PaCO₂) must be in the same unit.
- Base excess and bicarbonate are in mmol/L in both systems; only the partial pressures change.
Frequently asked questions
How do I convert kPa to mmHg?
Divide by 0.1333 (or multiply by about 7.50). Example: 8.0 kPa = 60.0 mmHg; 13.3 kPa = 99.8 mmHg.
How many mmHg is 1 kPa?
About 7.50 mmHg.
Does pH change when I convert units?
No. pH, bicarbonate and base excess are unaffected; only PaO₂ and PaCO₂ are converted.
Evidence and guidelines
- Primary source: NIST Special Publication 811 (2008), Guide for the Use of the International System of Units — Appendix B.8/B.9 conversion factors: 1 lb = 0.45359237 kg, 1 in = 2.54 cm, 1 mmHg = 133.322 Pa, t/°C = (t/°F − 32)/1.8.
- BIPM. The International System of Units (SI), 9th edition, 2019 — Table 8 (non-SI units accepted for use with the SI, incl. litre) and the definition of the kelvin and degree Celsius.
Have a follow-up question?
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Related calculators
- Pressure (blood gas) mmHg → kPaConvert pressure (blood gas) from mmHg to kPa
- PaO₂/FiO₂ ratio (ARDS severity, Berlin)Oxygenation index with Berlin ARDS severity grading; PaO₂ in kPa or mmHg
- A–a oxygen gradientAlveolar–arterial O₂ difference from a blood gas, in kPa (mmHg input accepted)
- Winters’ formula in kPaExpected pCO₂ in metabolic acidosis for blood gas analysers reporting kPa
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