Convert Pound per square inch to Millimetre of mercury
1 pound per square inch = 51.71493 millimetre of mercury (mmHg). For example, 10 pound per square inch = 517.1493 millimetre of mercury and 100 pound per square inch = 5,171.493 millimetre of mercury. Type any value below to convert pound per square inch to millimetre of mercury both ways β it runs entirely in your browser.
Quick answer: Pound per square inch to Millimetre of mercury
1 Pound per square inch = 51.71493 Millimetre of mercury (psi β mmHg). To convert pound per square inch to millimetre of mercury, multiply by 51.71493. To convert millimetre of mercury to pound per square inch, multiply by 0.01933678. 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 pound per square inch-to-millimetre of mercury questions.
How to convert Pound per square inch to Millimetre of mercury
To convert pound per square inch to millimetre of mercury, multiply the number of pound per square inch by the conversion factor 51.71493, because 1 psi = 51.71493 mmHg. The conversion is linear, so the same factor works for any value β whole numbers, decimals or fractions. For the reverse direction, 1 mmHg = 0.01933678 psi, so you divide by 51.71493 (or multiply by 0.01933678) to turn millimetre of mercury back into pound per square inch.
mmHg = psi Γ 51.71493 Β·
psi = mmHg Γ 0.01933678
- Write down the value you want to convert, in pound per square inch.
- Multiply it by 51.71493.
- The result is the same area/length/quantity expressed in millimetre of mercury.
Pound per square inch to Millimetre of mercury β worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 pound per square inch is 258.5746 millimetre of mercury because 5 psi Γ 51.71493 = 258.5746 mmHg.
| Pound per square inch | Calculation | Millimetre of mercury |
|---|---|---|
| 1 psi | 1 psi Γ 51.71493 = 51.71493 mmHg | 51.71493 mmHg |
| 2 psi | 2 psi Γ 51.71493 = 103.4299 mmHg | 103.4299 mmHg |
| 3 psi | 3 psi Γ 51.71493 = 155.1448 mmHg | 155.1448 mmHg |
| 5 psi | 5 psi Γ 51.71493 = 258.5746 mmHg | 258.5746 mmHg |
| 7 psi | 7 psi Γ 51.71493 = 362.0045 mmHg | 362.0045 mmHg |
| 10 psi | 10 psi Γ 51.71493 = 517.1493 mmHg | 517.1493 mmHg |
| 12 psi | 12 psi Γ 51.71493 = 620.5791 mmHg | 620.5791 mmHg |
| 15 psi | 15 psi Γ 51.71493 = 775.7239 mmHg | 775.7239 mmHg |
| 20 psi | 20 psi Γ 51.71493 = 1,034.299 mmHg | 1,034.299 mmHg |
| 25 psi | 25 psi Γ 51.71493 = 1,292.873 mmHg | 1,292.873 mmHg |
| 50 psi | 50 psi Γ 51.71493 = 2,585.746 mmHg | 2,585.746 mmHg |
| 100 psi | 100 psi Γ 51.71493 = 5,171.493 mmHg | 5,171.493 mmHg |
Common Pound per square inch to Millimetre of mercury conversions
These are the pound per square inch-to-millimetre of mercury values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 pound per square inch = 51.71493 millimetre of mercury
- 2 pound per square inch = 103.4299 millimetre of mercury
- 2.5 pound per square inch = 129.2873 millimetre of mercury
- 3 pound per square inch = 155.1448 millimetre of mercury
- 4 pound per square inch = 206.8597 millimetre of mercury
- 5 pound per square inch = 258.5746 millimetre of mercury
- 6 pound per square inch = 310.2896 millimetre of mercury
- 7 pound per square inch = 362.0045 millimetre of mercury
- 8 pound per square inch = 413.7194 millimetre of mercury
- 9 pound per square inch = 465.4343 millimetre of mercury
- 10 pound per square inch = 517.1493 millimetre of mercury
- 12 pound per square inch = 620.5791 millimetre of mercury
- 15 pound per square inch = 775.7239 millimetre of mercury
- 20 pound per square inch = 1,034.299 millimetre of mercury
- 25 pound per square inch = 1,292.873 millimetre of mercury
- 30 pound per square inch = 1,551.448 millimetre of mercury
- 50 pound per square inch = 2,585.746 millimetre of mercury
- 75 pound per square inch = 3,878.619 millimetre of mercury
- 100 pound per square inch = 5,171.493 millimetre of mercury
- 200 pound per square inch = 10,342.99 millimetre of mercury
- 500 pound per square inch = 25,857.46 millimetre of mercury
- 1000 pound per square inch = 51,714.93 millimetre of mercury
Pound per square inch to Millimetre of mercury conversion chart (both directions)
The chart below converts pound per square inch to millimetre of mercury and millimetre of mercury to pound per square inch side by side, so it works whichever way you need. 1 pound per square inch = 51.71493 millimetre of mercury, and 1 millimetre of mercury = 0.01933678 pound per square inch.
| Pound per square inch β Millimetre of mercury | Millimetre of mercury β Pound per square inch |
|---|---|
| 0.25 psi = 12.92873 mmHg | 0.25 mmHg = 0.004834194 psi |
| 0.5 psi = 25.85746 mmHg | 0.5 mmHg = 0.009668389 psi |
| 1 psi = 51.71493 mmHg | 1 mmHg = 0.01933678 psi |
| 2 psi = 103.4299 mmHg | 2 mmHg = 0.03867355 psi |
| 3 psi = 155.1448 mmHg | 3 mmHg = 0.05801033 psi |
| 4 psi = 206.8597 mmHg | 4 mmHg = 0.07734711 psi |
| 5 psi = 258.5746 mmHg | 5 mmHg = 0.09668389 psi |
| 6 psi = 310.2896 mmHg | 6 mmHg = 0.1160207 psi |
| 7 psi = 362.0045 mmHg | 7 mmHg = 0.1353574 psi |
| 8 psi = 413.7194 mmHg | 8 mmHg = 0.1546942 psi |
| 9 psi = 465.4343 mmHg | 9 mmHg = 0.174031 psi |
| 10 psi = 517.1493 mmHg | 10 mmHg = 0.1933678 psi |
| 12 psi = 620.5791 mmHg | 12 mmHg = 0.2320413 psi |
| 15 psi = 775.7239 mmHg | 15 mmHg = 0.2900517 psi |
| 20 psi = 1,034.299 mmHg | 20 mmHg = 0.3867355 psi |
| 25 psi = 1,292.873 mmHg | 25 mmHg = 0.4834194 psi |
| 30 psi = 1,551.448 mmHg | 30 mmHg = 0.5801033 psi |
| 40 psi = 2,068.597 mmHg | 40 mmHg = 0.7734711 psi |
| 50 psi = 2,585.746 mmHg | 50 mmHg = 0.9668389 psi |
| 75 psi = 3,878.619 mmHg | 75 mmHg = 1.450258 psi |
| 100 psi = 5,171.493 mmHg | 100 mmHg = 1.933678 psi |
| 150 psi = 7,757.239 mmHg | 150 mmHg = 2.900517 psi |
| 200 psi = 10,342.99 mmHg | 200 mmHg = 3.867355 psi |
| 250 psi = 12,928.73 mmHg | 250 mmHg = 4.834194 psi |
| 500 psi = 25,857.46 mmHg | 500 mmHg = 9.668389 psi |
| 1000 psi = 51,714.93 mmHg | 1000 mmHg = 19.33678 psi |
Pound per square inch vs Millimetre of mercury: 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 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.
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.
Convert 1 Pound per square inch to other units
It can help to see a pound per square inch next to the other units it is commonly compared with. 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 |
Convert 1 Millimetre of mercury to other units
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 |
Tips for converting Pound per square inch to Millimetre of mercury
- To go from pound per square inch to millimetre of mercury, multiply by 51.71493; to go back, divide by 51.71493 (or multiply by 0.01933678).
- For a quick mental estimate, remember that 1 pound per square inch β 51.71493 millimetre of mercury, so 10 pound per square inch β 517.1493 millimetre of mercury.
- 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 Pound per square inch to Millimetre of mercury converter
Type a number into the Pound per square inch field and the equivalent in Millimetre of mercury 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 Millimetre of mercury field to convert the other way (millimetre of mercury to pound per square inch). 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 psi = 51.71493 mmHg), 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 pound per square inch-to-millimetre of mercury 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 millimetre of mercury are in 1 pound per square inch?
- 1 pound per square inch = 51.71493 millimetre of mercury (mmHg). To convert any number of pound per square inch to millimetre of mercury, multiply by 51.71493.
- How do I convert pound per square inch to millimetre of mercury?
- Multiply the number of pound per square inch by 51.71493. For example, 10 pound per square inch = 10 Γ 51.71493 = 517.1493 millimetre of mercury, and 25 pound per square inch = 1,292.873 millimetre of mercury.
- How many pound per square inch are in 1 millimetre of mercury?
- 1 millimetre of mercury = 0.01933678 pound per square inch. So to convert millimetre of mercury back to pound per square inch, multiply by 0.01933678.
- What is the formula to convert pound per square inch to millimetre of mercury?
- millimetre of mercury = pound per square inch Γ 51.71493. The reverse formula is pound per square inch = millimetre of mercury Γ 0.01933678.
- How much is 100 pound per square inch in millimetre of mercury?
- 100 pound per square inch = 5,171.493 millimetre of mercury. (And 1000 pound per square inch = 51,714.93 millimetre of mercury.)
- Which is bigger, a pound per square inch or a millimetre of mercury?
- A pound per square inch is larger: 1 pound per square inch = 51.71493 millimetre of mercury.
- Is this pound per square inch to millimetre of mercury converter accurate?
- Yes β every value is computed from the exact 51.71493 mmHg per psi factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert millimetre of mercury to pound per square inch too?
- Yes. The converter works both ways β enter a value in either field. 1 millimetre of mercury = 0.01933678 pound per square inch.