Convert Inches of Water to kgf/mm²
1 inch of water (inH₂O) = 0.0000254 kilograms-force per square millimetre (kgf/mm²). 1 kgf/mm² = 39370.07874 inH₂O. Example: 15 inH₂O = 15 × 0.0000254 = 0.000381 kgf/mm².
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1 inH₂O = 0.0000254 kgf/mm²
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk inch of water to kilogram-force per square millimetre converter to paste a column from Excel.
How to Convert Inch of Water to Kilogram-force per Square Millimetre
- 1 inH₂O = 0.0000254 kgf/mm²
- 1 kgf/mm² = 39370.07874 inH₂O
- Example: convert 15 inH₂O to kgf/mm²: 15 inH₂O = 15 × 0.0000254 kgf/mm² = 0.000381 kgf/mm²
Reference conditions. inH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C).
Formula
kgf/mm² = inH₂O × 0.0000254
or kgf/mm² = inH₂O ÷ 39370.07874016
Derivation from SI units:
- 1 inH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.0254 m = 249.08891 Pa
- 1 kgf/mm² = 9.80665 N ÷ 1 mm² = 9.80665 MPa (exact)
- 1 inH₂O = 249.08891 Pa ÷ 9806650 Pa per kgf/mm² = 0.0000254 kgf/mm²
Both units are defined exactly, so the factor is exact. Inch of Water definition: inch of water; Kilogram-force per Square Millimetre definition: kilogram-force per square millimetre.
Worked examples
- A reading of 0.3 inH₂O converts to 0.00000762 kgf/mm².
0.3 inH₂O × 0.0000254 = 0.00000762 kgf/mm² - A value of 3 inH₂O is 0.0000762 kgf/mm².
3 inH₂O × 0.0000254 = 0.0000762 kgf/mm²
Inch of Water to Kilogram-force per Square Millimetre conversion table
| Inches of Water (inH₂O) | Kilograms-force per Square Millimetre (kgf/mm²) |
|---|---|
| 0.01 inH₂O | 2.54 × 10⁻⁷ kgf/mm² |
| 0.02 inH₂O | 5.08 × 10⁻⁷ kgf/mm² |
| 0.03 inH₂O | 7.62 × 10⁻⁷ kgf/mm² |
| 0.05 inH₂O | 0.00000127 kgf/mm² |
| 0.1 inH₂O | 0.00000254 kgf/mm² |
| 0.15 inH₂O | 0.00000381 kgf/mm² |
| 0.2 inH₂O | 0.00000508 kgf/mm² |
| 0.25 inH₂O | 0.00000635 kgf/mm² |
| 0.3 inH₂O | 0.00000762 kgf/mm² |
| 0.4 inH₂O | 0.00001016 kgf/mm² |
| 0.5 inH₂O | 0.0000127 kgf/mm² |
| 0.75 inH₂O | 0.00001905 kgf/mm² |
| 1 inH₂O | 0.0000254 kgf/mm² |
| 1.5 inH₂O | 0.0000381 kgf/mm² |
| 2 inH₂O | 0.0000508 kgf/mm² |
| 2.5 inH₂O | 0.0000635 kgf/mm² |
| 3 inH₂O | 0.0000762 kgf/mm² |
| 4 inH₂O | 0.0001016 kgf/mm² |
| 5 inH₂O | 0.000127 kgf/mm² |
| 7 inH₂O | 0.0001778 kgf/mm² |
| 10 inH₂O | 0.000254 kgf/mm² |
| 11 inH₂O | 0.0002794 kgf/mm² |
| 14 inH₂O | 0.0003556 kgf/mm² |
| 20 inH₂O | 0.000508 kgf/mm² |
| 27.7 inH₂O | 0.00070358 kgf/mm² |
Where it's used
Inches of Water are used for HVAC total external static pressure (residential ≈ 0.5 inH₂O), while kilograms-force per square millimetre appear in tensile strength in older JIS and GB steel standards. 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 kilogram-force per square millimetre | 0.0000254 kgf/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 newton per square millimetre | 0.00024908891 N/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 kilograms-force per square millimetre are in 1 inch of water?
1 inH₂O = 0.0000254 kgf/mm².
How do I convert inches of water to kilograms-force per square millimetre?
Multiply the value in inH₂O by 0.0000254, or divide it by 39370.07874. For example, 15 inH₂O × 0.0000254 = 0.000381 kgf/mm².
Is the inH₂O to kgf/mm² conversion exact?
Yes. Both units are defined exactly, and 1 inH₂O is exactly 0.0000254 kgf/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)".
- 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, "kilogram-force per square millimeter".
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 kgf/mm². Retrieved October 25, 2026, from https://scientificconverters.com/pressure/inch-of-water-to-kilogram-force-per-square-millimeter/
IEEE
Scientific Converters, "Convert Inches of Water to kgf/mm²," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/pressure/inch-of-water-to-kilogram-force-per-square-millimeter/