• inHg   mH₂O
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Rounding Mode:

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?

A “meter of water @ 4°C” is a unique unit used primarily to measure pressure. At this specific temperature, water reaches its maximum density, and the pressure exerted by a one-meter column of water is approximately 9.81 kilopascals or 0.0979 atmospheres. This scenario represents the optimal conditions for standardizing pressure measurements because the physical properties of water are most stable, reducing variances in calculations.

This unit is especially important in fields like plumbing and hydraulics, where accurate pressure measurements are crucial. Understanding these principles can lead to better designs in water distribution systems, preventing common issues such as pipe bursts or inefficient water flow, ensuring systems operate safely and efficiently.

> Inches of mercury to Meters of water @ 4°C Conversion Table

Inches of mercury Meters of water @ 4°C
0 inHg 0 mH₂O
1 inHg 0.345316 mH₂O
2 inHg 0.690631 mH₂O
3 inHg 1.03595 mH₂O
4 inHg 1.38126 mH₂O
5 inHg 1.72658 mH₂O
6 inHg 2.07189 mH₂O
7 inHg 2.41721 mH₂O
8 inHg 2.76252 mH₂O
9 inHg 3.10784 mH₂O
10 inHg 3.45316 mH₂O
11 inHg 3.79847 mH₂O
12 inHg 4.14379 mH₂O
13 inHg 4.4891 mH₂O
14 inHg 4.83442 mH₂O
15 inHg 5.17973 mH₂O
16 inHg 5.52505 mH₂O
17 inHg 5.87036 mH₂O
18 inHg 6.21568 mH₂O
19 inHg 6.561 mH₂O
20 inHg 6.90631 mH₂O
21 inHg 7.25163 mH₂O
22 inHg 7.59694 mH₂O
23 inHg 7.94226 mH₂O
24 inHg 8.28757 mH₂O
25 inHg 8.63289 mH₂O
26 inHg 8.9782 mH₂O
27 inHg 9.32352 mH₂O
28 inHg 9.66884 mH₂O
29 inHg 10.01415 mH₂O
30 inHg 10.35947 mH₂O
31 inHg 10.70478 mH₂O
32 inHg 11.0501 mH₂O
33 inHg 11.39541 mH₂O
34 inHg 11.74073 mH₂O
35 inHg 12.08605 mH₂O
36 inHg 12.43136 mH₂O
37 inHg 12.77668 mH₂O
38 inHg 13.12199 mH₂O
39 inHg 13.46731 mH₂O
40 inHg 13.81262 mH₂O
41 inHg 14.15794 mH₂O
42 inHg 14.50325 mH₂O
43 inHg 14.84857 mH₂O
44 inHg 15.19389 mH₂O
45 inHg 15.5392 mH₂O
46 inHg 15.88452 mH₂O
47 inHg 16.22983 mH₂O
48 inHg 16.57515 mH₂O
49 inHg 16.92046 mH₂O
50 inHg 17.26578 mH₂O
51 inHg 17.61109 mH₂O
52 inHg 17.95641 mH₂O
53 inHg 18.30173 mH₂O
54 inHg 18.64704 mH₂O
55 inHg 18.99236 mH₂O
56 inHg 19.33767 mH₂O
57 inHg 19.68299 mH₂O
58 inHg 20.0283 mH₂O
59 inHg 20.37362 mH₂O
60 inHg 20.71893 mH₂O
61 inHg 21.06425 mH₂O
62 inHg 21.40957 mH₂O
63 inHg 21.75488 mH₂O
64 inHg 22.1002 mH₂O
65 inHg 22.44551 mH₂O
66 inHg 22.79083 mH₂O
67 inHg 23.13614 mH₂O
68 inHg 23.48146 mH₂O
69 inHg 23.82677 mH₂O
70 inHg 24.17209 mH₂O
71 inHg 24.51741 mH₂O
72 inHg 24.86272 mH₂O
73 inHg 25.20804 mH₂O
74 inHg 25.55335 mH₂O
75 inHg 25.89867 mH₂O
76 inHg 26.24398 mH₂O
77 inHg 26.5893 mH₂O
78 inHg 26.93461 mH₂O
79 inHg 27.27993 mH₂O
80 inHg 27.62525 mH₂O
81 inHg 27.97056 mH₂O
82 inHg 28.31588 mH₂O
83 inHg 28.66119 mH₂O
84 inHg 29.00651 mH₂O
85 inHg 29.35182 mH₂O
86 inHg 29.69714 mH₂O
87 inHg 30.04245 mH₂O
88 inHg 30.38777 mH₂O
89 inHg 30.73309 mH₂O
90 inHg 31.0784 mH₂O
91 inHg 31.42372 mH₂O
92 inHg 31.76903 mH₂O
93 inHg 32.11435 mH₂O
94 inHg 32.45966 mH₂O
95 inHg 32.80498 mH₂O
96 inHg 33.15029 mH₂O
97 inHg 33.49561 mH₂O
98 inHg 33.84093 mH₂O
99 inHg 34.18624 mH₂O
100 inHg 34.53156 mH₂O