• inHg   psi
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The “inch of mercury” (inHg) is a unit of pressure commonly used in aviation, meteorology, and refrigeration. It originates from the barometric pressure measurement practice using a column of mercury. This unit became a staple due to its early adoption in weather forecasting and its accurate and consistent measurements. An interesting fact is that an inch of mercury is approximately equal to 33.86 millibars or 3386 Pascals, but what truly distinguishes it is its historical significance in the development of modern atmospheric science.

In the 17th century, Evangelista Torricelli, a student of Galileo, first discovered that atmospheric pressure could sustain a column of mercury, laying the groundwork for this unit. His invention, the barometer, revolutionized how we understand and predict weather, marking the inch of mercury as more than just a unit—it’s a nod to the evolution of scientific inquiry and practice.

Did you know?

Pounds per square inch (psi) is a crucial unit of pressure measurement, widely used across various industries, including automotive, aviation, and even space exploration. One interesting fact is that a typical car tire is inflated to around 30 psi, but did you know that a commercial jetliner’s cabin is pressurized to a reduced level of 11 psi to simulate being at a comfortable altitude of about 6,000-8,000 feet? This helps passengers avoid the stress of low oxygen levels while flying at over 35,000 feet, where the atmospheric pressure is a meager 4 psi.

Moreover, psi is pivotal in assessing the force exerted on surfaces. If you’ve ever wondered why deep-sea submarines have thick hulls, it’s because they must withstand pressures of around 8,800 psi at depths of 6 miles beneath the ocean’s surface! This ensures safe exploration of the mysterious deep-sea world, showcasing psi’s significance in enabling human feats in extreme environments.

> Inches of mercury to Pounds per inch² Conversion Table

Inches of mercury Pounds per square inch
0 inHg 0 psi
1 inHg 0.491154 psi
2 inHg 0.982308 psi
3 inHg 1.47346 psi
4 inHg 1.96462 psi
5 inHg 2.45577 psi
6 inHg 2.94692 psi
7 inHg 3.43808 psi
8 inHg 3.92923 psi
9 inHg 4.42039 psi
10 inHg 4.91154 psi
11 inHg 5.40269 psi
12 inHg 5.89385 psi
13 inHg 6.385 psi
14 inHg 6.87616 psi
15 inHg 7.36731 psi
16 inHg 7.85846 psi
17 inHg 8.34962 psi
18 inHg 8.84077 psi
19 inHg 9.33193 psi
20 inHg 9.82308 psi
21 inHg 10.31423 psi
22 inHg 10.80539 psi
23 inHg 11.29654 psi
24 inHg 11.7877 psi
25 inHg 12.27885 psi
26 inHg 12.77 psi
27 inHg 13.26116 psi
28 inHg 13.75231 psi
29 inHg 14.24347 psi
30 inHg 14.73462 psi
31 inHg 15.22577 psi
32 inHg 15.71693 psi
33 inHg 16.20808 psi
34 inHg 16.69924 psi
35 inHg 17.19039 psi
36 inHg 17.68154 psi
37 inHg 18.1727 psi
38 inHg 18.66385 psi
39 inHg 19.15501 psi
40 inHg 19.64616 psi
41 inHg 20.13731 psi
42 inHg 20.62847 psi
43 inHg 21.11962 psi
44 inHg 21.61078 psi
45 inHg 22.10193 psi
46 inHg 22.59308 psi
47 inHg 23.08424 psi
48 inHg 23.57539 psi
49 inHg 24.06655 psi
50 inHg 24.5577 psi
51 inHg 25.04885 psi
52 inHg 25.54001 psi
53 inHg 26.03116 psi
54 inHg 26.52232 psi
55 inHg 27.01347 psi
56 inHg 27.50462 psi
57 inHg 27.99578 psi
58 inHg 28.48693 psi
59 inHg 28.97809 psi
60 inHg 29.46924 psi
61 inHg 29.96039 psi
62 inHg 30.45155 psi
63 inHg 30.9427 psi
64 inHg 31.43386 psi
65 inHg 31.92501 psi
66 inHg 32.41616 psi
67 inHg 32.90732 psi
68 inHg 33.39847 psi
69 inHg 33.88963 psi
70 inHg 34.38078 psi
71 inHg 34.87193 psi
72 inHg 35.36309 psi
73 inHg 35.85424 psi
74 inHg 36.3454 psi
75 inHg 36.83655 psi
76 inHg 37.3277 psi
77 inHg 37.81886 psi
78 inHg 38.31001 psi
79 inHg 38.80117 psi
80 inHg 39.29232 psi
81 inHg 39.78347 psi
82 inHg 40.27463 psi
83 inHg 40.76578 psi
84 inHg 41.25694 psi
85 inHg 41.74809 psi
86 inHg 42.23924 psi
87 inHg 42.7304 psi
88 inHg 43.22155 psi
89 inHg 43.71271 psi
90 inHg 44.20386 psi
91 inHg 44.69501 psi
92 inHg 45.18617 psi
93 inHg 45.67732 psi
94 inHg 46.16848 psi
95 inHg 46.65963 psi
96 inHg 47.15078 psi
97 inHg 47.64194 psi
98 inHg 48.13309 psi
99 inHg 48.62425 psi
100 inHg 49.1154 psi