Convert Millimeters of Water to Torr (mmH2O to Torr)
1 millimeter of water (mmH₂O) equals 0.07355592401 torr.
1 mmH₂O = 0.07355592401 Torr
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk millimeter of water to torr converter to paste a column from Excel.
How to Convert Millimeter of Water to Torr
- 1 mmH₂O = 0.07355592401 Torr
- 1 Torr = 13.59509806 mmH₂O
- Example: convert 15 mmH₂O to Torr: 15 mmH₂O = 15 × 0.07355592401 Torr = 1.10333886 Torr
Reference conditions. mmH₂O: Conventional water column: ρ = 1000 kg/m³ and gₙ = 9.80665 m/s² (≈ water at 4 °C).
Formula
Torr = mmH₂O × 0.07355592400691
or Torr = mmH₂O ÷ 13.59509806316
Derivation from SI units:
- 1 mmH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.001 m = 9.80665 Pa
- 1 Torr = 101325/760 Pa = 133.3223684 Pa (1/760 of a standard atmosphere)
- 1 mmH₂O = 9.80665 Pa ÷ 133.3223684211 Pa per Torr = 0.07355592400691 Torr
Both units are defined exactly, so the factor is exact. Millimeter of Water definition: millimeter of water; Torr definition: torr.
Worked examples
- A reading of 25 mmH₂O converts to 1.8388981 Torr.
25 mmH₂O × 0.07355592401 = 1.8388981 Torr - A value of 250 mmH₂O is 18.388981 Torr.
250 mmH₂O × 0.07355592401 = 18.388981 Torr
Millimeter of Water to Torr conversion table
| Millimeters of Water (mmH₂O) | Torr |
|---|---|
| 1 mmH₂O | 0.07355592401 Torr |
| 2 mmH₂O | 0.147111848 Torr |
| 5 mmH₂O | 0.36777962 Torr |
| 10 mmH₂O | 0.7355592401 Torr |
| 15 mmH₂O | 1.10333886 Torr |
| 20 mmH₂O | 1.47111848 Torr |
| 25 mmH₂O | 1.8388981 Torr |
| 30 mmH₂O | 2.20667772 Torr |
| 50 mmH₂O | 3.6777962 Torr |
| 75 mmH₂O | 5.516694301 Torr |
| 100 mmH₂O | 7.355592401 Torr |
| 150 mmH₂O | 11.0333886 Torr |
| 200 mmH₂O | 14.7111848 Torr |
| 250 mmH₂O | 18.388981 Torr |
| 300 mmH₂O | 22.0667772 Torr |
| 500 mmH₂O | 36.777962 Torr |
| 1000 mmH₂O | 73.55592401 Torr |
| 2000 mmH₂O | 147.111848 Torr |
| 5000 mmH₂O | 367.77962 Torr |
| 10000 mmH₂O | 735.5592401 Torr |
Where it's used
Millimeters of Water are used for fan static pressure and duct design in Asia and Europe, while torr appear in vacuum technology and vacuum gauges. Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.
Millimeter of Water to other pressure units
| Conversion | 1 mmH₂O equals |
|---|---|
| millimeter of water to pascal | 9.80665 Pa |
| millimeter of water to kilopascal | 0.00980665 kPa |
| millimeter of water to megapascal | 0.00000980665 MPa |
| millimeter of water to psi | 0.001422334331 psi |
| millimeter of water to bar | 0.0000980665 bar |
| millimeter of water to millibar | 0.0980665 mbar |
| millimeter of water to decibar | 0.000980665 dbar |
| millimeter of water to torr | 0.07355592401 Torr |
| millimeter of water to millimeter of mercury | 0.07355591353 mmHg |
| millimeter of water to centimeter of water | 0.1 cmH₂O |
| millimeter of water to inch of water | 0.03937007874 inH₂O |
| millimeter of water to inch of water (60 °F) | 0.03940945989 inH₂O (60 °F) |
| millimeter of water to inch of mercury | 0.002895902107 inHg |
| millimeter of water to atmosphere | 0.00009678411054 atm |
| millimeter of water to barye | 98.0665 Ba |
Frequently asked questions
How many torr are in 1 millimeter of water?
1 mmH₂O = 0.07355592401 Torr.
How do I convert millimeters of water to torr?
Multiply the value in mmH₂O by 0.07355592401, or divide it by 13.59509806. For example, 15 mmH₂O × 0.07355592401 = 1.10333886 Torr.
Is the mmH₂O to Torr 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, "millimeter of water, conventional (mmH2O)".
- 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, "torr (Torr)".
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 Millimeters of Water to Torr (mmH2O to Torr). Retrieved October 18, 2026, from https://scientificconverters.com/pressure/millimeter-of-water-to-torr/
IEEE
Scientific Converters, "Convert Millimeters of Water to Torr (mmH2O to Torr)," scientificconverters.com. Accessed: Oct. 18, 2026. [Online]. Available: https://scientificconverters.com/pressure/millimeter-of-water-to-torr/