Convert Inches of Water to Newtons per Square Millimetre
1 inch of water (inH₂O) = 0.00024908891 newtons per square millimetre (N/mm²). 1 N/mm² = 4014.63076 inH₂O. Example: 15 inH₂O = 15 × 0.00024908891 = 0.00373633365 N/mm².
Also searched as inches of water to N/mm2, inches of water in N/mm2, inches of water into newtons per square millimetre, inH2O to N/mm2, inH2O in newtons per square millimetre, inH2O into newton per square millimetre, inch of water to newton per square millimetre, inH2O to newtons per square millimetre converter, inches of water to newtons per square millimeter and how many newtons per square millimetre in an inch of water.
1 inH₂O = 0.00024908891 N/mm²
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk inch of water to newton per square millimetre converter to paste a column from Excel.
How to Convert Inch of Water to Newton per Square Millimetre
- 1 inH₂O = 0.00024908891 N/mm²
- 1 N/mm² = 4014.63076 inH₂O
- Example: convert 15 inH₂O to N/mm²: 15 inH₂O = 15 × 0.00024908891 N/mm² = 0.00373633365 N/mm²
Reference conditions. inH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C).
Formula
N/mm² = inH₂O × 0.00024908891
or N/mm² = inH₂O ÷ 4014.630759756
Derivation from SI units:
- 1 inH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.0254 m = 249.08891 Pa
- 1 N/mm² = 1 N ÷ 10⁻⁶ m² = 10⁶ Pa = 1 MPa
- 1 inH₂O = 249.08891 Pa ÷ 1000000 Pa per N/mm² = 0.00024908891 N/mm²
Both units are defined exactly, so the factor is exact. Inch of Water definition: inch of water; Newton per Square Millimetre definition: newton per square millimetre.
Worked examples
- A reading of 0.3 inH₂O converts to 0.000074726673 N/mm².
0.3 inH₂O × 0.00024908891 = 0.000074726673 N/mm² - A value of 3 inH₂O is 0.00074726673 N/mm².
3 inH₂O × 0.00024908891 = 0.00074726673 N/mm²
Inch of Water to Newton per Square Millimetre conversion table
| Inches of Water (inH₂O) | Newtons per Square Millimetre (N/mm²) |
|---|---|
| 0.01 inH₂O | 0.0000024908891 N/mm² |
| 0.02 inH₂O | 0.0000049817782 N/mm² |
| 0.03 inH₂O | 0.0000074726673 N/mm² |
| 0.05 inH₂O | 0.0000124544455 N/mm² |
| 0.1 inH₂O | 0.000024908891 N/mm² |
| 0.15 inH₂O | 0.0000373633365 N/mm² |
| 0.2 inH₂O | 0.000049817782 N/mm² |
| 0.25 inH₂O | 0.0000622722275 N/mm² |
| 0.3 inH₂O | 0.000074726673 N/mm² |
| 0.4 inH₂O | 0.000099635564 N/mm² |
| 0.5 inH₂O | 0.000124544455 N/mm² |
| 0.75 inH₂O | 0.0001868166825 N/mm² |
| 1 inH₂O | 0.00024908891 N/mm² |
| 1.5 inH₂O | 0.000373633365 N/mm² |
| 2 inH₂O | 0.00049817782 N/mm² |
| 2.5 inH₂O | 0.000622722275 N/mm² |
| 3 inH₂O | 0.00074726673 N/mm² |
| 4 inH₂O | 0.00099635564 N/mm² |
| 5 inH₂O | 0.00124544455 N/mm² |
| 7 inH₂O | 0.00174362237 N/mm² |
| 10 inH₂O | 0.0024908891 N/mm² |
| 11 inH₂O | 0.00273997801 N/mm² |
| 14 inH₂O | 0.00348724474 N/mm² |
| 20 inH₂O | 0.0049817782 N/mm² |
| 27.7 inH₂O | 0.006899762807 N/mm² |
Where it's used
Inches of Water are used for HVAC total external static pressure (residential ≈ 0.5 inH₂O), while newtons per square millimetre appear in steel yield and tensile strength (S355: 355 N/mm²). Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.
Inch of Water to other pressure units
| Conversion | 1 inH₂O equals |
|---|---|
| inch of water to newton per square millimetre | 0.00024908891 N/mm² |
| inch of water to pascal | 249.08891 Pa |
| inch of water to kilopascal | 0.24908891 kPa |
| inch of water to ksi | 0.000036127292 ksi |
| inch of water to kilogram-force per square centimetre | 0.00254 kgf/cm² |
| inch of water to psi | 0.036127292 psi |
| inch of water to bar | 0.0024908891 bar |
| inch of water to millimeter of mercury | 1.868320204 mmHg |
Show 12 more units
| inch of water to atmosphere | 0.002458316408 atm |
|---|---|
| inch of water to megapascal | 0.00024908891 MPa |
| inch of water to gigapascal | 2.4908891 × 10⁻⁷ GPa |
| inch of water to kilogram-force per square millimetre | 0.0000254 kgf/mm² |
| inch of water to millibar | 2.4908891 mbar |
| inch of water to torr | 1.86832047 Torr |
| 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 mercury | 0.07355591353 inHg |
| inch of water to decibar | 0.024908891 dbar |
| inch of water to inch of water (60 °F) | 1.001000281 inH₂O (60 °F) |
| inch of water to barye | 2490.8891 Ba |
Frequently asked questions
How many newtons per square millimetre are in 1 inch of water?
1 inH₂O = 0.00024908891 N/mm².
How do I convert inches of water to newtons per square millimetre?
Multiply the value in inH₂O by 0.00024908891, or divide it by 4014.63076. For example, 15 inH₂O × 0.00024908891 = 0.00373633365 N/mm².
Is the inH₂O to N/mm² conversion exact?
Yes. Both units are defined exactly, and 1 inH₂O is exactly 0.00024908891 N/mm².
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)".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 4, coherent derived units with special names.
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 Newtons per Square Millimetre. Retrieved October 25, 2026, from https://scientificconverters.com/pressure/inch-of-water-to-newton-per-square-millimeter/
IEEE
Scientific Converters, "Convert Inches of Water to Newtons per Square Millimetre," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/pressure/inch-of-water-to-newton-per-square-millimeter/