kPa to mmHg Converter
One millimetre of mercury is 133.322387415 pascals, so kilopascals to millimetres of mercury is one division: mmHg = kPa × 1,000 / 133.322387415, which is the same as multiplying by 7.50061575846. That makes 1 kPa 7.50061575846 mmHg, 10 kPa 75.0061575846 mmHg, 20 kPa 150.012315169 mmHg and 100 kPa 750.061575846 mmHg, and the reverse is exact to the factor itself: 1 mmHg is 0.133322387415 kPa. The 133.322387415 is a convention rather than a measurement of any particular column of mercury: it fixes the mercury density at 13,595.1 kg/m³ and gravity at the standard 9.80665 m/s², so the unit stays put while real mercury expands with temperature. This page opens with Kilopascal (kPa) in the From box and Millimetre of mercury (mmHg) in the To box, ahead of whatever pair the converter last remembered, and prints twelve significant digits. mmHg is flagged as an uncommon unit here, which affects only the list below the answer: the headline conversion works as normal, and ticking Show 1 more in the readout strip adds the mmHg row to the list beside pascals, bar, psi and atmospheres. The unit is the one printed on barometers, vacuum gauges and blood pressure cuffs, while the SI unit of pressure is the pascal. This page changes units and nothing else: it says nothing about what any reading means.
1 kPa in every pressure unit
Common questions
- How many mmHg is 1 kPa?
- 7.50061575846 mmHg, printed to twelve significant digits. It scales cleanly, so 2 kPa is 15.0012315169 mmHg, 5 kPa is 37.5030787923 mmHg, 16 kPa is 120.009852135 mmHg, 50 kPa is 375.030787923 mmHg and 100 kPa is 750.061575846 mmHg. Negative inputs are accepted for gauge readings below ambient, so -1 kPa returns -7.50061575846 mmHg.
- What is the formula for kPa to mmHg?
- mmHg = kPa × 1,000 / 133.322387415, or mmHg = kPa × 7.50061575846 if you prefer one multiplication. Going the other way, kPa = mmHg × 0.133322387415, so 760 mmHg is 101.325014435 kPa and 750 mmHg is 99.9917905612 kPa. The swap button between the two boxes reverses the pair and makes this an mmHg to kPa converter without a reload.
- Why is 101.325 kPa not exactly 760 mmHg here?
- Because two definitions of the mercury millimetre are in circulation and this converter holds one of them. The torr is defined as exactly 1/760 of a standard atmosphere, which works out to 133.32236842105 Pa. The conventional millimetre of mercury, the one in this table, is defined from mercury density and standard gravity as exactly 133.322387415 Pa. The two differ by about 1.4 parts in ten million, so 101.325 kPa reads 759.999891726 mmHg rather than 760, and 760 mmHg reads 101.325014435 kPa rather than 101.325. Both answers are right for their own definition, and they agree to seven digits.
- Is mmHg the same as torr?
- For everyday purposes yes, and in the defining documents no. A torr is 101,325/760 pascals exactly, an mmHg is 133.322387415 pascals exactly, and the gap between them shows up only in the eighth significant digit. This page prints the mmHg reading. If you need torr instead, the atmosphere row does the job directly: switch the To menu to Atmosphere (atm), where 101.325 kPa is exactly 1 atm and 1 kPa is 0.00986923266716 atm, then multiply by 760.
- Why is mmHg missing from the list under the answer?
- Because it is marked as an uncommon unit, and the list under the answer shows common units until you ask for the rest. Tick Show 1 more in the readout strip and the mmHg row appears. Nothing about the headline is affected: mmHg sits in both unit menus and the To box is already on it when you arrive. For 1 kPa, the list reads 1,000 Pa, 0.01 bar, 0.14503773773 psi and 0.00986923266716 atm, with 7.50061575846 mmHg added once the switch is on.
- How do I convert mmHg back to kPa?
- Press the swap button and the page becomes mmHg to kPa: 1 mmHg gives 0.133322387415 kPa, 750 mmHg gives 99.9917905612 kPa and 760 mmHg gives 101.325014435 kPa. The same reading in the other units of the list is there too, so 1 mmHg is 133.322387415 Pa, 0.00133322387415 bar, 0.0193367774595 psi and 0.00131578966114 atm.
- What is a kilopascal, and what is the base unit here?
- A pascal is one newton per square metre, and a kilopascal is exactly 1,000 of them, so 1 kPa is 1,000 Pa and 100 kPa is 1 bar. The readout strip under the boxes names the category, Pressure, and the base unit every factor in it is defined against, the pascal. The full pressure menu holds Pa, kPa, bar, psi and atm, with mmHg behind the Show 1 more switch.
- Does the converter know gauge pressure from absolute pressure?
- No, and no unit converter can: it scales the number you type and cannot see what the number was measured against. A gauge reading is relative to the surrounding air and an absolute reading is relative to vacuum, and the two differ by whatever the local atmospheric pressure is, which is 101.325 kPa at the standard value and reads 759.999891726 mmHg on this page. If your figure is a gauge figure, add that offset before converting, or the answer will be a correct conversion of the wrong quantity.
- Why does the page open on kPa and mmHg when I last converted something else?
- Because a page that names a pair should show that pair. This one sets kilopascals and millimetres of mercury on arrival, ahead of whatever the converter last remembered, and it leaves the main unit converter alone: go back to the converter itself and it is still on the pair you left it on. The number you last typed comes with you. Everything runs in your browser against a table of factors that ships with the page, with nothing uploaded and no account.
Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.