Convert Inches of Water to psi
1 inch of water (inH₂O) equals 0.036127292 psi.
1 inH₂O = 0.036127292 psi
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk inch of water to psi converter to paste a column from Excel.
How to Convert Inch of Water to psi
- 1 inH₂O = 0.036127292 psi
- 1 psi = 27.67990471 inH₂O
- Example: convert 15 inH₂O to psi: 15 inH₂O = 15 × 0.036127292 psi = 0.54190938 psi
Reference conditions. inH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C).
Formula
psi = inH₂O × 0.03612729200008
or psi = inH₂O ÷ 27.6799047102
Derivation from SI units:
- 1 inH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.0254 m = 249.08891 Pa
- 1 psi = 1 lbf/in² = (0.45359237 kg × 9.80665 m/s²) ÷ (0.0254 m)² = 6894.757293168 Pa
- 1 inH₂O = 249.08891 Pa ÷ 6894.757293168 Pa per psi = 0.03612729200008 psi
Both units are defined exactly, so the factor is exact. Inch of Water definition: inch of water; psi definition: psi.
Worked examples
- A 14 inH₂O gas supply equals 0.505782088 psi.
14 inH₂O × 0.036127292 = 0.505782088 psi - A dust collector with 6 inH₂O across its filter bags is at 0.216763752 psi.
6 inH₂O × 0.036127292 = 0.216763752 psi
Inch of Water to psi conversion table
| Inches of Water (inH₂O) | psi |
|---|---|
| 0.01 inH₂O | 0.00036127292 psi |
| 0.02 inH₂O | 0.00072254584 psi |
| 0.03 inH₂O | 0.00108381876 psi |
| 0.05 inH₂O | 0.0018063646 psi |
| 0.1 inH₂O | 0.0036127292 psi |
| 0.15 inH₂O | 0.0054190938 psi |
| 0.2 inH₂O | 0.0072254584 psi |
| 0.25 inH₂O | 0.009031823 psi |
| 0.3 inH₂O | 0.0108381876 psi |
| 0.4 inH₂O | 0.0144509168 psi |
| 0.5 inH₂O | 0.018063646 psi |
| 0.75 inH₂O | 0.027095469 psi |
| 1 inH₂O | 0.036127292 psi |
| 1.5 inH₂O | 0.054190938 psi |
| 2 inH₂O | 0.072254584 psi |
| 2.5 inH₂O | 0.09031823 psi |
| 3 inH₂O | 0.108381876 psi |
| 4 inH₂O | 0.144509168 psi |
| 5 inH₂O | 0.18063646 psi |
| 7 inH₂O | 0.252891044 psi |
| 10 inH₂O | 0.36127292 psi |
| 11 inH₂O | 0.397400212 psi |
| 14 inH₂O | 0.505782088 psi |
| 20 inH₂O | 0.72254584 psi |
| 27.7 inH₂O | 1.000725988 psi |
Where it's used
Gas regulators and pressure switches are often rated in psi, while appliances list inches of water column. About 28 inH₂O make 1 psi.
Inch of Water to other pressure units
| Conversion | 1 inH₂O equals |
|---|---|
| inch of water to pascal | 249.08891 Pa |
| inch of water to kilopascal | 0.24908891 kPa |
| inch of water to megapascal | 0.00024908891 MPa |
| inch of water to psi | 0.036127292 psi |
| inch of water to bar | 0.0024908891 bar |
| inch of water to millibar | 2.4908891 mbar |
| inch of water to decibar | 0.024908891 dbar |
| inch of water to torr | 1.86832047 Torr |
| inch of water to millimeter of mercury | 1.868320204 mmHg |
| inch of water to millimeter of water | 25.4 mmH₂O |
| inch of water to centimeter of water | 2.54 cmH₂O |
| inch of water to inch of water (60 °F) | 1.001000281 inH₂O (60 °F) |
| inch of water to inch of mercury | 0.07355591353 inHg |
| inch of water to atmosphere | 0.002458316408 atm |
| inch of water to barye | 2490.8891 Ba |
Frequently asked questions
Is 14 inches of water equal to 0.5 psi?
Close: 14 inH₂O = 0.5058 psi. The common "14 in WC ≈ ½ psi" rule is good to about 1 %.
How many psi are in 1 inch of water?
1 inH₂O = 0.036127292 psi.
How do I convert inches of water to psi?
Multiply the value in inH₂O by 0.036127292, or divide it by 27.67990471. For example, 15 inH₂O × 0.036127292 = 0.54190938 psi.
Is the inH₂O to psi conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "inch of water, conventional (inH2O)".
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "pound-force per square inch (psi)".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert Inches of Water to psi. Retrieved October 17, 2026, from https://scientificconverters.com/pressure/inch-of-water-to-psi/
IEEE
Scientific Converters, "Convert Inches of Water to psi," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/pressure/inch-of-water-to-psi/