Direct conversion
Convert pound per square inch [psi] to millimeter of water [mmH2O] instantly with formula, examples, chart, and FAQs.
1 pound per square inch [psi] = 703.06958 millimeter of water [mmH2O]
1 pound per square inch [psi] = 703.06958 millimeter of water [mmH2O]
Example: 1 pound per square inch [psi] equals 703.06958 millimeter of water [mmH2O].
Pressure conversions use pascal as the reference unit and include common engineering, weather, tire, and laboratory pressure units.
Displayed results are rounded for readability. The calculator keeps enough precision for everyday use and switches to scientific notation for very large or very small values. Last reviewed: 2026-08-14.
Pound per square inch is a pressure unit showing pounds-force applied over one square inch.
HistoryPSI comes from imperial force and area units and remains common in mechanical and pressure-gauge contexts.
Current usePSI is used for tire pressure, compressors, plumbing, hydraulics, gas cylinders, and equipment ratings.
The millimeter of water (mmH2O) is a pressure unit used to express measurements in this converter.
HistoryThis unit is included because it appears in practical measurement systems, technical references, product specifications, or everyday conversion needs.
Current useUse millimeter of water when comparing pressure values, checking specifications, converting between systems, or preparing quick estimates.
| pound per square inch [psi] | millimeter of water [mmH2O] |
|---|---|
| 1 | 703.06958 |
| 2 | 1406.139159 |
| 5 | 3515.347898 |
| 10 | 7030.695796 |
| 20 | 14061.391593 |
| 25 | 17576.739491 |
| 50 | 35153.478982 |
| 100 | 70306.957964 |
| 1000 | 703069.579639 |
Use this formula: 1 pound per square inch [psi] = 703.06958 millimeter of water [mmH2O] Enter your value in the calculator and the result updates instantly.
1 pound per square inch [psi] equals 703.06958 millimeter of water [mmH2O].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.