inHg to mmH2O Converter
Pressure · unit-converter
Convert inHg to mmH2O with a fixed input and output unit, step-by-step formula line, and reference tables. All calculations bridge through pascal with fixed definitions (standard atmosphere = 101,325 Pa; torr and mmHg = atm/760; plus industrial/manometer units like kgf/cm², inHg, inH2O, and mmH2O).
About inHg
Inches of mercury (inHg) is used in aviation altimetry and vacuum readings in some US contexts.
About mmH2O
Millimeters of water column (mmH2O) is used for very low differential pressure in instrumentation and ventilation.
How to convert inch of mercury (inhg) to millimeter of water (mmh2o, 4 °c)
1 inhg equals 345.31549080368933 mmh2o in this tool (via pascal):
1 inhg = (3386.38815789 Pa ÷ 9.80665 Pa) mmh2o = 345.31549080368933 mmh2o
Each inhg carries 3386.38815789 Pa and each mmh2o 9.80665 Pa, so one inhg equals 3386.38815789 ÷ 9.80665 mmh2o.
Let p(inhg) be pressure in inHg (inhg), and p(mmh2o) in mmH2O (mmh2o). Then:
p(mmh2o) = p(inhg) × (3386.38815789 / 9.80665)
Equivalently, divide by how many inhg fit into one mmh2o (Pa per mmh2o divided by Pa per inhg):
p(mmh2o) = p(inhg) ÷ 0.0028959025199610765
Examples
Example #1: Convert 1 inhg to mmh2o
1 inhg = 1 inhg × (3386.38815789/9.80665) mmh2o = 345.315490804 mmh2o
1 inhg = 1 inhg ÷ 0.0028959025199610765 = 345.315490804 mmh2o
1 inhg × (3,386.38815789/9.80665) = 345.315491 mmh2o
Example #2: Convert 10 inhg to mmh2o
10 inhg = 10 inhg × (3386.38815789/9.80665) mmh2o = 3453.15490804 mmh2o
10 inhg = 10 inhg ÷ 0.0028959025199610765 = 3453.15490804 mmh2o
10 inhg × (3,386.38815789/9.80665) = 3,453.154908 mmh2o
Summary
To convert inHg to mmH2O, multiply the value in inhg by (3386.38815789 Pa per inhg) / (9.80665 Pa per mmh2o). Equivalently: value_mmh2o = value_inhg × (3386.38815789 / 9.80665). Numerically, 1 inhg equals 345.31549080368933 mmh2o.
Relationship context
Both inHg and mmH2O are converted by fixed multiples of the pascal. Multiplying by (Pa per inhg) ÷ (Pa per mmh2o) gives the same result as passing through pascal, keeping bar, atm, PSI, kPa, hPa, torr, and mmHg consistent on the hub.
Conversion tables
| inHg (inhg) | mmH2O (mmh2o) |
|---|---|
| 0.1 | 34.5315490804 |
| 1 | 345.315490804 |
| 2 | 690.630981607 |
| 3 | 1,035.94647241 |
| 4 | 1,381.26196321 |
| 5 | 1,726.57745402 |
| 6 | 2,071.89294482 |
| 7 | 2,417.20843563 |
| 8 | 2,762.52392643 |
| 9 | 3,107.83941723 |
| inHg (inhg) | mmH2O (mmh2o) |
|---|---|
| 10 | 3,453.15490804 |
| 20 | 6,906.30981607 |
| 30 | 10,359.4647241 |
| 40 | 13,812.6196321 |
| 50 | 17,265.7745402 |
| 60 | 20,718.9294482 |
| 70 | 24,172.0843563 |
| 80 | 27,625.2392643 |
| 90 | 31,078.3941723 |
| 100 | 34,531.5490804 |