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Convert Inches of mercury to Pounds per square inch

1 inch of mercury is 0.491154 psi. One inch of mercury is exactly 0.491154199634 pounds per square inch.

One inch of mercury is 0.4911542 pounds per square inch. To convert inches of mercury to pounds per square inch, multiply by 0.4911542; to go the other way, divide by 0.4911542 or multiply by 2.0360205. The factor is exact rather than rounded: it follows from NIST Special Publication 811. The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals.

Factor checked against the defining standard · How we check

Pounds per square inch
0.491154 psi
Inches of mercury × 0.4911542
value * 0.4911541996340.491 psi

1 inch of mercury in every pressure unit

UnitValueExact factor
pounds per square inch0.4911541996 psi× 0.491154199634
bars0.03386389 bar× 0.03386389
pascals3,386.389 Pa× 3,386.389
kilopascals3.386389 kPa× 3.386389
megapascals0.003386389 MPa× 0.003386389
atmospheres0.03342106094 atm× 0.0334210609425
torr25.40000632 Torr× 25.4000063163
inches of mercury (as entered)1 inHg

Factors are entered by hand from NIST Special Publication 811 rather than derived from a units library, so the ones that terminate are exact rather than rounded.

How do you convert inches of mercury to pounds per square inch?

  1. 1.Take the measurement in inches of mercury.
  2. 2.Multiply by 0.4911542 — that is how many pounds per square inch fit in one inch of mercury.
  3. 3.To go back the other way, divide by 0.4911542, or multiply by 2.0360205.

Worked example: 25 inches of mercury to pounds per square inch

Formula
inHg × 0.4911542 = psi
Arithmetic
25 × 0.4911542 = 12.278855 psi
Answer
25 inHg = 12.278855 psi

The factor is rounded for display; the figure above is computed from the full value.

Inches of mercury to pounds per square inch conversion table

Inches of mercuryPounds per square inch
1 inHg0.491154 psi
2 inHg0.982308 psi
3 inHg1.473463 psi
4 inHg1.964617 psi
5 inHg2.455771 psi
6 inHg2.946925 psi
7 inHg3.438079 psi
8 inHg3.929234 psi
9 inHg4.420388 psi
10 inHg4.911542 psi
12 inHg5.89385 psi
15 inHg7.367313 psi
20 inHg9.823084 psi
25 inHg12.278855 psi
50 inHg24.55771 psi
100 inHg49.11542 psi
200 inHg98.23084 psi
300 inHg147.34626 psi
500 inHg245.5771 psi
1000 inHg491.1542 psi
2000 inHg982.308399 psi
5000 inHg2,455.770998 psi
10000 inHg4,911.541996 psi

What is an inch of mercury?

The pressure of a one-inch column of mercury at 0 °C, fixed by convention at 3,386.389 pascals. US aviation altimeters and barometers read in it.

What is a pound per square inch?

A pound-force spread over a square inch. Exact, because both parts are: it is 4.4482216152605 newtons divided by an inch squared. Every US tyre gauge, air line and pressure washer is marked in it.

How many pounds per square inch are in an inch of mercury?

One inch of mercury is 0.4911542 pounds per square inch. Going the other way, one pound per square inch is 2.0360205 inches of mercury. Both figures come from the same defined relation rather than from a measurement, which is why they are the same today as they were in 1959.

Every pressure unit here

UnitSymbolOne of these is
Pounds per square inchpsi6894.7573 pascal
Barsbar100000 pascal
PascalsPathe base unit
KilopascalskPa1000 pascal
MegapascalsMPa1000000 pascal
Atmospheresatm101325 pascal
TorrTorr133.32237 pascal
Inches of mercuryinHg3386.389 pascal

Source: NIST Special Publication 811 — pound-force is exactly 4.4482216152605 N and the inch exactly 0.0254 m

Questions people actually ask

How many pounds per square inch are in an inch of mercury?
0.4911542. A pound-force spread over a square inch. Exact, because both parts are: it is 4.4482216152605 newtons divided by an inch squared. Every US tyre gauge, air line and pressure washer is marked in it.
How do I convert pounds per square inch back to inches of mercury?
Divide by 0.4911542, or multiply by 2.0360205 — they are the same operation.

Other pressure conversions

Pounds per square inch to inches of mercury — the same conversion the other way.