Convert psi to Inches of Water
1 psi equals 27.67990471 inches of water (inH₂O).
1 psi = 27.67990471 inH₂O
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk psi to inch of water converter to paste a column from Excel.
How to Convert psi to Inch of Water
- 1 psi = 27.67990471 inH₂O
- 1 inH₂O = 0.036127292 psi
- Example: convert 15 psi to inH₂O: 15 psi = 15 × 27.67990471 inH₂O = 415.1985707 inH₂O
Reference conditions. inH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C).
Formula
inH₂O = psi × 27.6799047102
Derivation from SI units:
- 1 psi = 1 lbf/in² = (0.45359237 kg × 9.80665 m/s²) ÷ (0.0254 m)² = 6894.757293168 Pa
- 1 inH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.0254 m = 249.08891 Pa
- 1 psi = 6894.757293168 Pa ÷ 249.08891 Pa per inH₂O = 27.6799047102 inH₂O
Both units are defined exactly, so the factor is exact. psi definition: psi; Inch of Water definition: inch of water.
Worked examples
- An elevated-pressure gas system at 0.5 psi delivers 13.83995236 inH₂O.
0.5 psi × 27.67990471 = 13.83995236 inH₂O - 1 psi is 27.67990471 inH₂O, so small differentials read more clearly in inches of water.
1 psi × 27.67990471 = 27.67990471 inH₂O
psi to Inch of Water conversion table
| psi | Inches of Water (inH₂O) |
|---|---|
| 0.01 psi | 0.2767990471 inH₂O |
| 0.05 psi | 1.383995236 inH₂O |
| 0.1 psi | 2.767990471 inH₂O |
| 0.25 psi | 6.919976178 inH₂O |
| 0.5 psi | 13.83995236 inH₂O |
| 1 psi | 27.67990471 inH₂O |
| 2 psi | 55.35980942 inH₂O |
| 5 psi | 138.3995236 inH₂O |
| 10 psi | 276.7990471 inH₂O |
| 14.7 psi | 406.8945992 inH₂O |
| 15 psi | 415.1985707 inH₂O |
| 20 psi | 553.5980942 inH₂O |
| 25 psi | 691.9976178 inH₂O |
| 30 psi | 830.3971413 inH₂O |
| 32 psi | 885.7569507 inH₂O |
| 35 psi | 968.7966649 inH₂O |
| 40 psi | 1107.196188 inH₂O |
| 50 psi | 1383.995236 inH₂O |
| 60 psi | 1660.794283 inH₂O |
| 80 psi | 2214.392377 inH₂O |
| 100 psi | 2767.990471 inH₂O |
| 125 psi | 3459.988089 inH₂O |
| 150 psi | 4151.985707 inH₂O |
| 200 psi | 5535.980942 inH₂O |
| 500 psi | 13839.95236 inH₂O |
| 1000 psi | 27679.90471 inH₂O |
| 3000 psi | 83039.71413 inH₂O |
| 5000 psi | 138399.5236 inH₂O |
Where it's used
Low-pressure gas, HVAC and dust-collector readings switch from psi to inches of water because in WC gives more readable numbers below about 1 psi. One psi is about 27.7 inH₂O.
psi to other pressure units
| Conversion | 1 psi equals |
|---|---|
| psi to pascal | 6894.757293 Pa |
| psi to kilopascal | 6.894757293 kPa |
| psi to megapascal | 0.006894757293 MPa |
| psi to bar | 0.06894757293 bar |
| psi to millibar | 68.94757293 mbar |
| psi to decibar | 0.6894757293 dbar |
| psi to torr | 51.71493257 Torr |
| psi to millimeter of mercury | 51.7149252 mmHg |
| psi to millimeter of water | 703.0695796 mmH₂O |
| psi to centimeter of water | 70.30695796 cmH₂O |
| psi to inch of water | 27.67990471 inH₂O |
| psi to inch of water (60 °F) | 27.7075924 inH₂O (60 °F) |
| psi to inch of mercury | 2.036020677 inHg |
| psi to atmosphere | 0.06804596391 atm |
| psi to barye | 68947.57293 Ba |
Frequently asked questions
How many inches of water is 1 psi?
1 psi = 27.67990471 inH₂O (conventional inH₂O).
How many inches of water are in 1 psi?
1 psi = 27.67990471 inH₂O.
How do I convert psi to inches of water?
Multiply the value in psi by 27.67990471. For example, 15 psi × 27.67990471 = 415.1985707 inH₂O.
Is the psi to inH₂O 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, "pound-force per square inch (psi)".
- 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)".
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 psi to Inches of Water. Retrieved October 17, 2026, from https://scientificconverters.com/pressure/psi-to-inch-of-water/
IEEE
Scientific Converters, "Convert psi to Inches of Water," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/pressure/psi-to-inch-of-water/