Convert Millimetre of mercury to Pound per square inch
1 millimetre of mercury = 0.01933678 pound per square inch (psi). For example, 10 millimetre of mercury = 0.1933678 pound per square inch and 100 millimetre of mercury = 1.933678 pound per square inch. Type any value below to convert millimetre of mercury to pound per square inch both ways β it runs entirely in your browser.
Quick answer: Millimetre of mercury to Pound per square inch
1 Millimetre of mercury = 0.01933678 Pound per square inch (mmHg β psi). To convert millimetre of mercury to pound per square inch, multiply by 0.01933678. To convert pound per square inch to millimetre of mercury, multiply by 51.71493. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common millimetre of mercury-to-pound per square inch questions.
How to convert Millimetre of mercury to Pound per square inch
To convert millimetre of mercury to pound per square inch, multiply the number of millimetre of mercury by the conversion factor 0.01933678, because 1 mmHg = 0.01933678 psi. The conversion is linear, so the same factor works for any value β whole numbers, decimals or fractions. For the reverse direction, 1 psi = 51.71493 mmHg, so you divide by 0.01933678 (or multiply by 51.71493) to turn pound per square inch back into millimetre of mercury.
psi = mmHg Γ 0.01933678 Β·
mmHg = psi Γ 51.71493
- Write down the value you want to convert, in millimetre of mercury.
- Multiply it by 0.01933678.
- The result is the same area/length/quantity expressed in pound per square inch.
Millimetre of mercury to Pound per square inch β worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 millimetre of mercury is 0.09668389 pound per square inch because 5 mmHg Γ 0.01933678 = 0.09668389 psi.
| Millimetre of mercury | Calculation | Pound per square inch |
|---|---|---|
| 1 mmHg | 1 mmHg Γ 0.01933678 = 0.01933678 psi | 0.01933678 psi |
| 2 mmHg | 2 mmHg Γ 0.01933678 = 0.03867355 psi | 0.03867355 psi |
| 3 mmHg | 3 mmHg Γ 0.01933678 = 0.05801033 psi | 0.05801033 psi |
| 5 mmHg | 5 mmHg Γ 0.01933678 = 0.09668389 psi | 0.09668389 psi |
| 7 mmHg | 7 mmHg Γ 0.01933678 = 0.1353574 psi | 0.1353574 psi |
| 10 mmHg | 10 mmHg Γ 0.01933678 = 0.1933678 psi | 0.1933678 psi |
| 12 mmHg | 12 mmHg Γ 0.01933678 = 0.2320413 psi | 0.2320413 psi |
| 15 mmHg | 15 mmHg Γ 0.01933678 = 0.2900517 psi | 0.2900517 psi |
| 20 mmHg | 20 mmHg Γ 0.01933678 = 0.3867355 psi | 0.3867355 psi |
| 25 mmHg | 25 mmHg Γ 0.01933678 = 0.4834194 psi | 0.4834194 psi |
| 50 mmHg | 50 mmHg Γ 0.01933678 = 0.9668389 psi | 0.9668389 psi |
| 100 mmHg | 100 mmHg Γ 0.01933678 = 1.933678 psi | 1.933678 psi |
Common Millimetre of mercury to Pound per square inch conversions
These are the millimetre of mercury-to-pound per square inch values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 millimetre of mercury = 0.01933678 pound per square inch
- 2 millimetre of mercury = 0.03867355 pound per square inch
- 2.5 millimetre of mercury = 0.04834194 pound per square inch
- 3 millimetre of mercury = 0.05801033 pound per square inch
- 4 millimetre of mercury = 0.07734711 pound per square inch
- 5 millimetre of mercury = 0.09668389 pound per square inch
- 6 millimetre of mercury = 0.1160207 pound per square inch
- 7 millimetre of mercury = 0.1353574 pound per square inch
- 8 millimetre of mercury = 0.1546942 pound per square inch
- 9 millimetre of mercury = 0.174031 pound per square inch
- 10 millimetre of mercury = 0.1933678 pound per square inch
- 12 millimetre of mercury = 0.2320413 pound per square inch
- 15 millimetre of mercury = 0.2900517 pound per square inch
- 20 millimetre of mercury = 0.3867355 pound per square inch
- 25 millimetre of mercury = 0.4834194 pound per square inch
- 30 millimetre of mercury = 0.5801033 pound per square inch
- 50 millimetre of mercury = 0.9668389 pound per square inch
- 75 millimetre of mercury = 1.450258 pound per square inch
- 100 millimetre of mercury = 1.933678 pound per square inch
- 200 millimetre of mercury = 3.867355 pound per square inch
- 500 millimetre of mercury = 9.668389 pound per square inch
- 1000 millimetre of mercury = 19.33678 pound per square inch
Millimetre of mercury to Pound per square inch conversion chart (both directions)
The chart below converts millimetre of mercury to pound per square inch and pound per square inch to millimetre of mercury side by side, so it works whichever way you need. 1 millimetre of mercury = 0.01933678 pound per square inch, and 1 pound per square inch = 51.71493 millimetre of mercury.
| Millimetre of mercury β Pound per square inch | Pound per square inch β Millimetre of mercury |
|---|---|
| 0.25 mmHg = 0.004834194 psi | 0.25 psi = 12.92873 mmHg |
| 0.5 mmHg = 0.009668389 psi | 0.5 psi = 25.85746 mmHg |
| 1 mmHg = 0.01933678 psi | 1 psi = 51.71493 mmHg |
| 2 mmHg = 0.03867355 psi | 2 psi = 103.4299 mmHg |
| 3 mmHg = 0.05801033 psi | 3 psi = 155.1448 mmHg |
| 4 mmHg = 0.07734711 psi | 4 psi = 206.8597 mmHg |
| 5 mmHg = 0.09668389 psi | 5 psi = 258.5746 mmHg |
| 6 mmHg = 0.1160207 psi | 6 psi = 310.2896 mmHg |
| 7 mmHg = 0.1353574 psi | 7 psi = 362.0045 mmHg |
| 8 mmHg = 0.1546942 psi | 8 psi = 413.7194 mmHg |
| 9 mmHg = 0.174031 psi | 9 psi = 465.4343 mmHg |
| 10 mmHg = 0.1933678 psi | 10 psi = 517.1493 mmHg |
| 12 mmHg = 0.2320413 psi | 12 psi = 620.5791 mmHg |
| 15 mmHg = 0.2900517 psi | 15 psi = 775.7239 mmHg |
| 20 mmHg = 0.3867355 psi | 20 psi = 1,034.299 mmHg |
| 25 mmHg = 0.4834194 psi | 25 psi = 1,292.873 mmHg |
| 30 mmHg = 0.5801033 psi | 30 psi = 1,551.448 mmHg |
| 40 mmHg = 0.7734711 psi | 40 psi = 2,068.597 mmHg |
| 50 mmHg = 0.9668389 psi | 50 psi = 2,585.746 mmHg |
| 75 mmHg = 1.450258 psi | 75 psi = 3,878.619 mmHg |
| 100 mmHg = 1.933678 psi | 100 psi = 5,171.493 mmHg |
| 150 mmHg = 2.900517 psi | 150 psi = 7,757.239 mmHg |
| 200 mmHg = 3.867355 psi | 200 psi = 10,342.99 mmHg |
| 250 mmHg = 4.834194 psi | 250 psi = 12,928.73 mmHg |
| 500 mmHg = 9.668389 psi | 500 psi = 25,857.46 mmHg |
| 1000 mmHg = 19.33678 psi | 1000 psi = 51,714.93 mmHg |
Millimetre of mercury vs Pound per square inch: which is bigger?
A pound per square inch is the larger unit: one pound per square inch equals 51.71493 millimetre of mercurys. Put another way, you need 51.71493 millimetre of mercurys to make a single pound per square inch.
What is a Millimetre of mercury? History, origin and usage
Measuring pressure by the height of a mercury column dates to Torricelli in 1643 and became the standard laboratory method for three centuries. Mercury was chosen because it is dense enough to keep the tube a manageable length β a water barometer measuring the same pressure would need to be over ten metres tall. The modern unit no longer depends on real mercury: it is fixed at exactly 133.322387415 pascals, the value a millimetre of mercury would give at a conventional density of 13,595.1 kg per cubic metre under standard gravity.
Millimetres of mercury are the universal unit of blood pressure β a reading of "120 over 80" means 120 mmHg when the heart contracts and 80 mmHg between beats. They are also used for eye pressure, cerebrospinal fluid pressure and some vacuum work.
Mercury sphygmomanometers are being retired worldwide because of the toxicity of mercury, yet the unit has outlived the instrument: digital monitors with no mercury in them still report in mmHg, because a century of medical guidance is written in it.
What is a Pound per square inch? History, origin and usage
Pounds per square inch grew directly out of the steam age: boiler safety valves were rated by how many pounds of weight it took to hold them shut over a known area, and the unit survived into every later technology that Britain and the United States industrialised. It never went through a formal international definition of its own β instead it became exact in 1959, when the yard-and-pound agreement fixed the pound and the inch exactly, and again through the fixing of standard gravity, which pins down what a "pound of force" means.
Psi is the standard pressure unit in the United States and remains widely understood in Britain, India and elsewhere: tyre pressures, air compressors, pressure washers, water mains, hydraulic lines and scuba tanks. Car tyres are commonly inflated to around 30 to 35 psi.
Psi is exactly defined but its value in pascals is a decimal that repeats forever, so any written figure is necessarily rounded somewhere. Gauges usually read gauge pressure β the amount above surrounding air β which is why a flat tyre reads zero rather than about 14.7.
Convert 1 Millimetre of mercury to other units
It can help to see a millimetre of mercury next to the other units it is commonly compared with. One millimetre of mercury (mmHg) is equal to:
| 1 Millimetre of mercury equals | Unit |
|---|---|
| 133.3224 Pa | Pascal |
| 1.333224 hPa | Hectopascal |
| 0.1333224 kPa | Kilopascal |
| 0.0001333224 MPa | Megapascal |
| 1.333224 mbar | Millibar |
| 0.001333224 bar | Bar |
| 0.00131579 atm | Standard atmosphere |
| 1 Torr | Torr |
| 0.03937008 inHg | Inch of mercury |
| 13.5951 mmHβO | Millimetre of water |
| 0.5352402 inHβO | Inch of water |
| 0.01933678 psi | Pound per square inch |
| 0.00135951 kgf/cmΒ² | Kilogram-force per square centimetre |
Convert 1 Pound per square inch to other units
One pound per square inch (psi) is equal to:
| 1 Pound per square inch equals | Unit |
|---|---|
| 6,894.757 Pa | Pascal |
| 68.94757 hPa | Hectopascal |
| 6.894757 kPa | Kilopascal |
| 0.006894757 MPa | Megapascal |
| 68.94757 mbar | Millibar |
| 0.06894757 bar | Bar |
| 0.06804596 atm | Standard atmosphere |
| 51.71493 Torr | Torr |
| 51.71493 mmHg | Millimetre of mercury |
| 2.036021 inHg | Inch of mercury |
| 703.0696 mmHβO | Millimetre of water |
| 27.6799 inHβO | Inch of water |
| 0.07030696 kgf/cmΒ² | Kilogram-force per square centimetre |
Tips for converting Millimetre of mercury to Pound per square inch
- To go from millimetre of mercury to pound per square inch, multiply by 0.01933678; to go back, divide by 0.01933678 (or multiply by 51.71493).
- For a quick mental estimate, remember that 1 millimetre of mercury β 0.01933678 pound per square inch, so 10 millimetre of mercury β 0.1933678 pound per square inch.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type β change either side to convert in that direction.
How to use this Millimetre of mercury to Pound per square inch converter
Type a number into the Millimetre of mercury field and the equivalent in Pound per square inch appears instantly β there is no βconvertβ button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Pound per square inch field to convert the other way (pound per square inch to millimetre of mercury). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above β use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page β the formula, the worked examples, the conversion chart and the βconvert to other unitsβ tables β is computed from a single verified conversion factor (1 mmHg = 0.01933678 psi), never copied from a hand-typed lookup table that could drift. That factor is derived from each unitβs definition in terms of a common base unit, and an automated check re-verifies all of the siteβs factors on every update, so the numbers here stay correct over time. This matters for millimetre of mercury-to-pound per square inch conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- NIST Special Publication 811 β Guide for the Use of the SI β publishes the exact metric equivalents of the customary pressure units. A psi is one pound of force over one square inch, and the 1959 international yard-and-pound agreement fixes the pound at exactly 0.453 592 37 kilogram and the inch at exactly 0.0254 metre, while standard gravity is fixed at exactly 9.806 65 m/sΒ² β so psi, inches of mercury and inches of water are defined exactly rather than measured.
- BIPM β The International System of Units (SI Brochure) β the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
Pressure factors here come from fixed definitions, anchored to the pascal: a bar is exactly 100,000 Pa, one atmosphere is exactly 101,325 Pa, a torr is exactly a 760th of an atmosphere, and psi is built from the exact pound and the exact inch. Two of them β psi and the torr β work out to decimals that repeat forever, so where a number is shown rounded it is marked, not quietly trimmed.
Frequently asked questions
- How many pound per square inch are in 1 millimetre of mercury?
- 1 millimetre of mercury = 0.01933678 pound per square inch (psi). To convert any number of millimetre of mercury to pound per square inch, multiply by 0.01933678.
- How do I convert millimetre of mercury to pound per square inch?
- Multiply the number of millimetre of mercury by 0.01933678. For example, 10 millimetre of mercury = 10 Γ 0.01933678 = 0.1933678 pound per square inch, and 25 millimetre of mercury = 0.4834194 pound per square inch.
- How many millimetre of mercury are in 1 pound per square inch?
- 1 pound per square inch = 51.71493 millimetre of mercury. So to convert pound per square inch back to millimetre of mercury, multiply by 51.71493.
- What is the formula to convert millimetre of mercury to pound per square inch?
- pound per square inch = millimetre of mercury Γ 0.01933678. The reverse formula is millimetre of mercury = pound per square inch Γ 51.71493.
- How much is 100 millimetre of mercury in pound per square inch?
- 100 millimetre of mercury = 1.933678 pound per square inch. (And 1000 millimetre of mercury = 19.33678 pound per square inch.)
- Which is bigger, a millimetre of mercury or a pound per square inch?
- A pound per square inch is larger: 1 pound per square inch = 51.71493 millimetre of mercury.
- Is this millimetre of mercury to pound per square inch converter accurate?
- Yes β every value is computed from the exact 0.01933678 psi per mmHg factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert pound per square inch to millimetre of mercury too?
- Yes. The converter works both ways β enter a value in either field. 1 pound per square inch = 51.71493 millimetre of mercury.