Convert Inch of mercury to Pound per square inch
1 inch of mercury = 0.4911541 pound per square inch (psi). For example, 10 inch of mercury = 4.911541 pound per square inch and 100 inch of mercury = 49.11541 pound per square inch. Type any value below to convert inch of mercury to pound per square inch both ways — it runs entirely in your browser.
Quick answer: Inch of mercury to Pound per square inch
1 Inch of mercury = 0.4911541 Pound per square inch (inHg → psi). To convert inch of mercury to pound per square inch, multiply by 0.4911541. To convert pound per square inch to inch of mercury, multiply by 2.036021. 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 inch of mercury-to-pound per square inch questions.
How to convert Inch of mercury to Pound per square inch
To convert inch of mercury to pound per square inch, multiply the number of inch of mercury by the conversion factor 0.4911541, because 1 inHg = 0.4911541 psi. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 psi = 2.036021 inHg, so you divide by 0.4911541 (or multiply by 2.036021) to turn pound per square inch back into inch of mercury.
psi = inHg × 0.4911541 ·
inHg = psi × 2.036021
- Write down the value you want to convert, in inch of mercury.
- Multiply it by 0.4911541.
- The result is the same area/length/quantity expressed in pound per square inch.
Inch of mercury to Pound per square inch — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 inch of mercury is 2.455771 pound per square inch because 5 inHg × 0.4911541 = 2.455771 psi.
| Inch of mercury | Calculation | Pound per square inch |
|---|---|---|
| 1 inHg | 1 inHg × 0.4911541 = 0.4911541 psi | 0.4911541 psi |
| 2 inHg | 2 inHg × 0.4911541 = 0.9823083 psi | 0.9823083 psi |
| 3 inHg | 3 inHg × 0.4911541 = 1.473462 psi | 1.473462 psi |
| 5 inHg | 5 inHg × 0.4911541 = 2.455771 psi | 2.455771 psi |
| 7 inHg | 7 inHg × 0.4911541 = 3.438079 psi | 3.438079 psi |
| 10 inHg | 10 inHg × 0.4911541 = 4.911541 psi | 4.911541 psi |
| 12 inHg | 12 inHg × 0.4911541 = 5.89385 psi | 5.89385 psi |
| 15 inHg | 15 inHg × 0.4911541 = 7.367312 psi | 7.367312 psi |
| 20 inHg | 20 inHg × 0.4911541 = 9.823083 psi | 9.823083 psi |
| 25 inHg | 25 inHg × 0.4911541 = 12.27885 psi | 12.27885 psi |
| 50 inHg | 50 inHg × 0.4911541 = 24.55771 psi | 24.55771 psi |
| 100 inHg | 100 inHg × 0.4911541 = 49.11541 psi | 49.11541 psi |
Common Inch of mercury to Pound per square inch conversions
These are the inch 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 inch of mercury = 0.4911541 pound per square inch
- 2 inch of mercury = 0.9823083 pound per square inch
- 2.5 inch of mercury = 1.227885 pound per square inch
- 3 inch of mercury = 1.473462 pound per square inch
- 4 inch of mercury = 1.964617 pound per square inch
- 5 inch of mercury = 2.455771 pound per square inch
- 6 inch of mercury = 2.946925 pound per square inch
- 7 inch of mercury = 3.438079 pound per square inch
- 8 inch of mercury = 3.929233 pound per square inch
- 9 inch of mercury = 4.420387 pound per square inch
- 10 inch of mercury = 4.911541 pound per square inch
- 12 inch of mercury = 5.89385 pound per square inch
- 15 inch of mercury = 7.367312 pound per square inch
- 20 inch of mercury = 9.823083 pound per square inch
- 25 inch of mercury = 12.27885 pound per square inch
- 30 inch of mercury = 14.73462 pound per square inch
- 50 inch of mercury = 24.55771 pound per square inch
- 75 inch of mercury = 36.83656 pound per square inch
- 100 inch of mercury = 49.11541 pound per square inch
- 200 inch of mercury = 98.23083 pound per square inch
- 500 inch of mercury = 245.5771 pound per square inch
- 1000 inch of mercury = 491.1541 pound per square inch
Inch of mercury to Pound per square inch conversion chart (both directions)
The chart below converts inch of mercury to pound per square inch and pound per square inch to inch of mercury side by side, so it works whichever way you need. 1 inch of mercury = 0.4911541 pound per square inch, and 1 pound per square inch = 2.036021 inch of mercury.
| Inch of mercury → Pound per square inch | Pound per square inch → Inch of mercury |
|---|---|
| 0.25 inHg = 0.1227885 psi | 0.25 psi = 0.5090052 inHg |
| 0.5 inHg = 0.2455771 psi | 0.5 psi = 1.01801 inHg |
| 1 inHg = 0.4911541 psi | 1 psi = 2.036021 inHg |
| 2 inHg = 0.9823083 psi | 2 psi = 4.072041 inHg |
| 3 inHg = 1.473462 psi | 3 psi = 6.108062 inHg |
| 4 inHg = 1.964617 psi | 4 psi = 8.144083 inHg |
| 5 inHg = 2.455771 psi | 5 psi = 10.1801 inHg |
| 6 inHg = 2.946925 psi | 6 psi = 12.21612 inHg |
| 7 inHg = 3.438079 psi | 7 psi = 14.25214 inHg |
| 8 inHg = 3.929233 psi | 8 psi = 16.28817 inHg |
| 9 inHg = 4.420387 psi | 9 psi = 18.32419 inHg |
| 10 inHg = 4.911541 psi | 10 psi = 20.36021 inHg |
| 12 inHg = 5.89385 psi | 12 psi = 24.43225 inHg |
| 15 inHg = 7.367312 psi | 15 psi = 30.54031 inHg |
| 20 inHg = 9.823083 psi | 20 psi = 40.72041 inHg |
| 25 inHg = 12.27885 psi | 25 psi = 50.90052 inHg |
| 30 inHg = 14.73462 psi | 30 psi = 61.08062 inHg |
| 40 inHg = 19.64617 psi | 40 psi = 81.44083 inHg |
| 50 inHg = 24.55771 psi | 50 psi = 101.801 inHg |
| 75 inHg = 36.83656 psi | 75 psi = 152.7016 inHg |
| 100 inHg = 49.11541 psi | 100 psi = 203.6021 inHg |
| 150 inHg = 73.67312 psi | 150 psi = 305.4031 inHg |
| 200 inHg = 98.23083 psi | 200 psi = 407.2041 inHg |
| 250 inHg = 122.7885 psi | 250 psi = 509.0052 inHg |
| 500 inHg = 245.5771 psi | 500 psi = 1,018.01 inHg |
| 1000 inHg = 491.1541 psi | 1000 psi = 2,036.021 inHg |
Inch 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 2.036021 inch of mercurys. Put another way, you need 2.036021 inch of mercurys to make a single pound per square inch.
What is a Inch of mercury? History, origin and usage
Inches of mercury come from the same barometers as millimetres of mercury, read off in imperial units. The unit stayed embedded in North American practice long after the metric system spread elsewhere, largely because aviation and broadcast weather standardised on it early and changing would have meant reissuing every altimeter and every chart.
Inches of mercury are used for atmospheric pressure in United States weather reports and, importantly, for altimeter settings in aviation in the US and Canada. They also appear on vacuum gauges for engines and air-conditioning work.
The standard sea-level pressure of 29.92 inHg is one of the most recognisable numbers in aviation — pilots set it as the default altimeter reference. An inch of mercury is exactly 25.4 millimetres of mercury, because the inch itself has been exactly 25.4 mm since 1959.
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 — 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 — the amount above surrounding air — which is why a flat tyre reads zero rather than about 14.7.
Convert 1 Inch of mercury to other units
It can help to see a inch of mercury next to the other units it is commonly compared with. One inch of mercury (inHg) is equal to:
| 1 Inch of mercury equals | Unit |
|---|---|
| 3,386.389 Pa | Pascal |
| 33.86389 hPa | Hectopascal |
| 3.386389 kPa | Kilopascal |
| 0.003386389 MPa | Megapascal |
| 33.86389 mbar | Millibar |
| 0.03386389 bar | Bar |
| 0.03342106 atm | Standard atmosphere |
| 25.4 Torr | Torr |
| 25.4 mmHg | Millimetre of mercury |
| 345.3155 mmH₂O | Millimetre of water |
| 13.5951 inH₂O | Inch of water |
| 0.4911541 psi | Pound per square inch |
| 0.03453155 kgf/cm² | 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 mmH₂O | Millimetre of water |
| 27.6799 inH₂O | Inch of water |
| 0.07030696 kgf/cm² | Kilogram-force per square centimetre |
Tips for converting Inch of mercury to Pound per square inch
- To go from inch of mercury to pound per square inch, multiply by 0.4911541; to go back, divide by 0.4911541 (or multiply by 2.036021).
- For a quick mental estimate, remember that 1 inch of mercury ≈ 0.4911541 pound per square inch, so 10 inch of mercury ≈ 4.911541 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 — change either side to convert in that direction.
How to use this Inch of mercury to Pound per square inch converter
Type a number into the Inch of mercury field and the equivalent in Pound per square inch appears instantly — there is no “convert” 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 inch 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 — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 inHg = 0.4911541 psi), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for inch 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 — Guide for the Use of the SI — 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/s² — so psi, inches of mercury and inches of water are defined exactly rather than measured.
- BIPM — The International System of Units (SI Brochure) — 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 — psi and the torr — 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 inch of mercury?
- 1 inch of mercury = 0.4911541 pound per square inch (psi). To convert any number of inch of mercury to pound per square inch, multiply by 0.4911541.
- How do I convert inch of mercury to pound per square inch?
- Multiply the number of inch of mercury by 0.4911541. For example, 10 inch of mercury = 10 × 0.4911541 = 4.911541 pound per square inch, and 25 inch of mercury = 12.27885 pound per square inch.
- How many inch of mercury are in 1 pound per square inch?
- 1 pound per square inch = 2.036021 inch of mercury. So to convert pound per square inch back to inch of mercury, multiply by 2.036021.
- What is the formula to convert inch of mercury to pound per square inch?
- pound per square inch = inch of mercury × 0.4911541. The reverse formula is inch of mercury = pound per square inch × 2.036021.
- How much is 100 inch of mercury in pound per square inch?
- 100 inch of mercury = 49.11541 pound per square inch. (And 1000 inch of mercury = 491.1541 pound per square inch.)
- Which is bigger, a inch of mercury or a pound per square inch?
- A pound per square inch is larger: 1 pound per square inch = 2.036021 inch of mercury.
- Is this inch of mercury to pound per square inch converter accurate?
- Yes — every value is computed from the exact 0.4911541 psi per inHg factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert pound per square inch to inch of mercury too?
- Yes. The converter works both ways — enter a value in either field. 1 pound per square inch = 2.036021 inch of mercury.