About the mmHg to kPa Converter
This mmHg to kPa converter changes a pressure in millimetres of mercury into kilopascals and shows the same reading in torr, inches of mercury, hectopascals (millibars), psi, atmospheres and pascals. You can also start from any of those units, so it works equally well as a kPa to mmHg or inHg to hPa converter.
Millimetres of mercury are still the standard unit for blood pressure and many medical gas readings, while kPa is used in SI-based textbooks, engineering specs and for blood-gas results (PaO₂, PaCO₂) in the UK, Europe and Australia. Weather reports use hPa (millibars) in most of the world and inches of mercury in the US and aviation, and vacuum gauges often read in torr.
The conversion uses the conventional definition 1 mmHg = 133.322387415 Pa. One torr is defined slightly differently (1/760 of a standard atmosphere), but the two differ by only about one part in seven million, so they are interchangeable for any practical reading.
With the default inputs, the converted pressure is 15.9987. Change any value above to recalculate instantly.
How to use the mmhg to kpa converter
- 1Type the pressure reading.
- 2Choose the unit it is in (mmHg, kPa, inHg, hPa, psi, atm, torr or Pa).
- 3Choose the unit you want as the headline answer.
- 4Read the converted value and the same pressure in every other unit below.
Formula and method
One millimetre of mercury is the pressure exerted by a 1 mm column of mercury of density 13.5951 g/cm³ under standard gravity, which works out to 133.322387415 pascals. Dividing by 1,000 gives kilopascals, so multiply mmHg by 0.1333224 to get kPa, or multiply kPa by 7.50062 to go back.
For the other units the calculator first converts your reading to pascals, then divides by each unit’s size: 1 inHg = 3,386.389 Pa, 1 hPa = 100 Pa, 1 psi = 6,894.757 Pa, 1 atm = 101,325 Pa and 1 torr = 101,325 ÷ 760 Pa. Readings are treated as absolute or gauge exactly as entered — the tool does not add or remove atmospheric pressure.
- mmHg
- Pressure in millimetres of mercury
- kPa
- Pressure in kilopascals (1,000 Pa)
Worked examples
Systolic blood pressure of 120 mmHg
120 × 133.322387 Pa = 15,998.7 Pa, which is 15.999 kPa. The same reading is 2.32 psi or 4.72 inHg.
Standard atmosphere in kPa to mmHg
Sea-level standard pressure is 101.325 kPa. Dividing 101,325 Pa by 133.3224 Pa per mmHg gives 760 mmHg (29.92 inHg, 14.70 psi).
Barometer reading of 29.92 inHg
The US altimeter setting of 29.92 inHg × 3,386.389 Pa = 101,321 Pa, or 1,013.2 hPa — the standard pressure used on weather maps.
Diastolic 80 mmHg
80 × 0.1333224 = 10.666 kPa, so a reading of 120/80 mmHg is about 16.0/10.7 kPa.
Frequently asked questions
How do I convert mmHg to kPa?+
Multiply the mmHg value by 0.133322. For example 120 mmHg × 0.133322 = 16.0 kPa. For a mental estimate, divide mmHg by 7.5.
How do I convert kPa to mmHg?+
Multiply kilopascals by 7.50062. So 10 kPa is 75.0 mmHg and 101.325 kPa (one standard atmosphere) is 760 mmHg.
Is torr the same as mmHg?+
Almost. One torr is exactly 1/760 of a standard atmosphere (133.3224 Pa), while one mmHg is 133.3224 Pa based on mercury density. They differ by about 0.000015%, so they are treated as equal in practice.
What is normal blood pressure in kPa?+
A reading of 120/80 mmHg is about 16.0/10.7 kPa. Blood pressure is almost always reported in mmHg, even in countries that otherwise use SI units; kPa appears mainly in some older literature and SI-only textbooks.
How many hPa are in one inHg?+
One inch of mercury equals 33.8639 hPa (millibars). Standard sea-level pressure of 1,013.25 hPa is 29.9213 inHg, usually rounded to 29.92 inHg (1,013.2 hPa).
Why is blood pressure still measured in mmHg?+
Early sphygmomanometers used a column of mercury, and clinical thresholds were built around those readings. Modern digital monitors still report mmHg so results stay comparable with guidelines.