Convert Millimetre of water to Pascal
1 millimetre of water = 9.80665 pascal (Pa). For example, 10 millimetre of water = 98.0665 pascal and 100 millimetre of water = 980.665 pascal. Type any value below to convert millimetre of water to pascal both ways — it runs entirely in your browser.
Quick answer: Millimetre of water to Pascal
1 Millimetre of water = 9.80665 Pascal (mmH₂O → Pa). To convert millimetre of water to pascal, multiply by 9.80665. To convert pascal to millimetre of water, multiply by 0.1019716. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common millimetre of water-to-pascal questions.
How to convert Millimetre of water to Pascal
To convert millimetre of water to pascal, multiply the number of millimetre of water by the conversion factor 9.80665, because 1 mmH₂O = 9.80665 Pa. The conversion is linear, so the same factor works for any value — whole numbers, decimals or fractions. For the reverse direction, 1 Pa = 0.1019716 mmH₂O, so you divide by 9.80665 (or multiply by 0.1019716) to turn pascal back into millimetre of water.
Pa = mmH₂O × 9.80665 ·
mmH₂O = Pa × 0.1019716
- Write down the value you want to convert, in millimetre of water.
- Multiply it by 9.80665.
- The result is the same area/length/quantity expressed in pascal.
Millimetre of water to Pascal — worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 millimetre of water is 49.03325 pascal because 5 mmH₂O × 9.80665 = 49.03325 Pa.
| Millimetre of water | Calculation | Pascal |
|---|---|---|
| 1 mmH₂O | 1 mmH₂O × 9.80665 = 9.80665 Pa | 9.80665 Pa |
| 2 mmH₂O | 2 mmH₂O × 9.80665 = 19.6133 Pa | 19.6133 Pa |
| 3 mmH₂O | 3 mmH₂O × 9.80665 = 29.41995 Pa | 29.41995 Pa |
| 5 mmH₂O | 5 mmH₂O × 9.80665 = 49.03325 Pa | 49.03325 Pa |
| 7 mmH₂O | 7 mmH₂O × 9.80665 = 68.64655 Pa | 68.64655 Pa |
| 10 mmH₂O | 10 mmH₂O × 9.80665 = 98.0665 Pa | 98.0665 Pa |
| 12 mmH₂O | 12 mmH₂O × 9.80665 = 117.6798 Pa | 117.6798 Pa |
| 15 mmH₂O | 15 mmH₂O × 9.80665 = 147.0998 Pa | 147.0998 Pa |
| 20 mmH₂O | 20 mmH₂O × 9.80665 = 196.133 Pa | 196.133 Pa |
| 25 mmH₂O | 25 mmH₂O × 9.80665 = 245.1662 Pa | 245.1662 Pa |
| 50 mmH₂O | 50 mmH₂O × 9.80665 = 490.3325 Pa | 490.3325 Pa |
| 100 mmH₂O | 100 mmH₂O × 9.80665 = 980.665 Pa | 980.665 Pa |
Common Millimetre of water to Pascal conversions
These are the millimetre of water-to-pascal values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 millimetre of water = 9.80665 pascal
- 2 millimetre of water = 19.6133 pascal
- 2.5 millimetre of water = 24.51662 pascal
- 3 millimetre of water = 29.41995 pascal
- 4 millimetre of water = 39.2266 pascal
- 5 millimetre of water = 49.03325 pascal
- 6 millimetre of water = 58.8399 pascal
- 7 millimetre of water = 68.64655 pascal
- 8 millimetre of water = 78.4532 pascal
- 9 millimetre of water = 88.25985 pascal
- 10 millimetre of water = 98.0665 pascal
- 12 millimetre of water = 117.6798 pascal
- 15 millimetre of water = 147.0998 pascal
- 20 millimetre of water = 196.133 pascal
- 25 millimetre of water = 245.1662 pascal
- 30 millimetre of water = 294.1995 pascal
- 50 millimetre of water = 490.3325 pascal
- 75 millimetre of water = 735.4987 pascal
- 100 millimetre of water = 980.665 pascal
- 200 millimetre of water = 1,961.33 pascal
- 500 millimetre of water = 4,903.325 pascal
- 1000 millimetre of water = 9,806.65 pascal
Millimetre of water to Pascal conversion chart (both directions)
The chart below converts millimetre of water to pascal and pascal to millimetre of water side by side, so it works whichever way you need. 1 millimetre of water = 9.80665 pascal, and 1 pascal = 0.1019716 millimetre of water.
| Millimetre of water → Pascal | Pascal → Millimetre of water |
|---|---|
| 0.25 mmH₂O = 2.451662 Pa | 0.25 Pa = 0.02549291 mmH₂O |
| 0.5 mmH₂O = 4.903325 Pa | 0.5 Pa = 0.05098581 mmH₂O |
| 1 mmH₂O = 9.80665 Pa | 1 Pa = 0.1019716 mmH₂O |
| 2 mmH₂O = 19.6133 Pa | 2 Pa = 0.2039432 mmH₂O |
| 3 mmH₂O = 29.41995 Pa | 3 Pa = 0.3059149 mmH₂O |
| 4 mmH₂O = 39.2266 Pa | 4 Pa = 0.4078865 mmH₂O |
| 5 mmH₂O = 49.03325 Pa | 5 Pa = 0.5098581 mmH₂O |
| 6 mmH₂O = 58.8399 Pa | 6 Pa = 0.6118297 mmH₂O |
| 7 mmH₂O = 68.64655 Pa | 7 Pa = 0.7138013 mmH₂O |
| 8 mmH₂O = 78.4532 Pa | 8 Pa = 0.815773 mmH₂O |
| 9 mmH₂O = 88.25985 Pa | 9 Pa = 0.9177446 mmH₂O |
| 10 mmH₂O = 98.0665 Pa | 10 Pa = 1.019716 mmH₂O |
| 12 mmH₂O = 117.6798 Pa | 12 Pa = 1.223659 mmH₂O |
| 15 mmH₂O = 147.0998 Pa | 15 Pa = 1.529574 mmH₂O |
| 20 mmH₂O = 196.133 Pa | 20 Pa = 2.039432 mmH₂O |
| 25 mmH₂O = 245.1662 Pa | 25 Pa = 2.549291 mmH₂O |
| 30 mmH₂O = 294.1995 Pa | 30 Pa = 3.059149 mmH₂O |
| 40 mmH₂O = 392.266 Pa | 40 Pa = 4.078865 mmH₂O |
| 50 mmH₂O = 490.3325 Pa | 50 Pa = 5.098581 mmH₂O |
| 75 mmH₂O = 735.4987 Pa | 75 Pa = 7.647872 mmH₂O |
| 100 mmH₂O = 980.665 Pa | 100 Pa = 10.19716 mmH₂O |
| 150 mmH₂O = 1,470.997 Pa | 150 Pa = 15.29574 mmH₂O |
| 200 mmH₂O = 1,961.33 Pa | 200 Pa = 20.39432 mmH₂O |
| 250 mmH₂O = 2,451.662 Pa | 250 Pa = 25.49291 mmH₂O |
| 500 mmH₂O = 4,903.325 Pa | 500 Pa = 50.98581 mmH₂O |
| 1000 mmH₂O = 9,806.65 Pa | 1000 Pa = 101.9716 mmH₂O |
Millimetre of water vs Pascal: which is bigger?
A millimetre of water is the larger unit: one millimetre of water equals 9.80665 pascals. Put another way, you need 9.80665 pascals to make a single millimetre of water.
What is a Millimetre of water? History, origin and usage
Water columns were the earliest way of measuring small pressures, because a simple U-shaped tube of water is cheap, visible and needs no calibration. They remained standard for ventilation and gas work long after mercury took over for larger pressures, since water is safe and its greater height makes small differences easy to read.
Millimetres of water measure very low pressures: ventilation ducts, fan performance curves, drainage and sewer gas testing, filter resistance and some respiratory equipment.
It is fixed at exactly 9.80665 pascals, the same number as standard gravity, because water was assigned a conventional density of exactly 1,000 kg per cubic metre. Water is about 13.6 times less dense than mercury, so a water column has to be about 13.6 times taller to show the same pressure.
What is a Pascal? History, origin and usage
The pascal is named after Blaise Pascal, who in 1648 had his brother-in-law carry a mercury barometer up the Puy de Dôme in central France and watch the mercury column fall as he climbed. That experiment showed air has weight and that the pressure it exerts drops with height. The unit itself is much younger: the name was adopted by the General Conference on Weights and Measures in 1971, replacing the older habit of writing pressures as "newtons per square metre".
The pascal is the SI unit of pressure and the base every other unit on this page is defined against. On its own it is awkwardly small for daily life — a sheet of paper resting on a table presses down with only a few pascals — so real-world figures are almost always given with a prefix: hectopascals for weather, kilopascals for tyres and gas, megapascals for concrete and hydraulics.
One pascal is one newton spread over one square metre, which is about the pressure of a five-rupee coin lying flat on a table. Because pressure is force divided by area, the same push concentrated into a smaller area gives a much higher pressure — which is why a drawing pin goes into a wall and your thumb does not.
Convert 1 Millimetre of water to other units
It can help to see a millimetre of water next to the other units it is commonly compared with. One millimetre of water (mmH₂O) is equal to:
| 1 Millimetre of water equals | Unit |
|---|---|
| 9.80665 Pa | Pascal |
| 0.0980665 hPa | Hectopascal |
| 0.00980665 kPa | Kilopascal |
| 0.00000980665 MPa | Megapascal |
| 0.0980665 mbar | Millibar |
| 0.0000980665 bar | Bar |
| 0.00009678411 atm | Standard atmosphere |
| 0.07355592 Torr | Torr |
| 0.07355591 mmHg | Millimetre of mercury |
| 0.002895902 inHg | Inch of mercury |
| 0.03937008 inH₂O | Inch of water |
| 0.001422334 psi | Pound per square inch |
| 0.0001 kgf/cm² | Kilogram-force per square centimetre |
Convert 1 Pascal to other units
One pascal (Pa) is equal to:
| 1 Pascal equals | Unit |
|---|---|
| 0.01 hPa | Hectopascal |
| 0.001 kPa | Kilopascal |
| 0.000001 MPa | Megapascal |
| 0.01 mbar | Millibar |
| 0.00001 bar | Bar |
| 0.000009869233 atm | Standard atmosphere |
| 0.007500617 Torr | Torr |
| 0.007500616 mmHg | Millimetre of mercury |
| 0.0002952998 inHg | Inch of mercury |
| 0.1019716 mmH₂O | Millimetre of water |
| 0.004014631 inH₂O | Inch of water |
| 0.0001450377 psi | Pound per square inch |
| 0.00001019716 kgf/cm² | Kilogram-force per square centimetre |
Tips for converting Millimetre of water to Pascal
- To go from millimetre of water to pascal, multiply by 9.80665; to go back, divide by 9.80665 (or multiply by 0.1019716).
- For a quick mental estimate, remember that 1 millimetre of water ≈ 9.80665 pascal, so 10 millimetre of water ≈ 98.0665 pascal.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type — change either side to convert in that direction.
How to use this Millimetre of water to Pascal converter
Type a number into the Millimetre of water field and the equivalent in Pascal appears instantly — there is no “convert” button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Pascal field to convert the other way (pascal to millimetre of water). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above — use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page — the formula, the worked examples, the conversion chart and the “convert to other units” tables — is computed from a single verified conversion factor (1 mmH₂O = 9.80665 Pa), never copied from a hand-typed lookup table that could drift. That factor is derived from each unit’s definition in terms of a common base unit, and an automated check re-verifies all of the site’s factors on every update, so the numbers here stay correct over time. This matters for millimetre of water-to-pascal conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM — The International System of Units (SI Brochure) — the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST — Definitions of the SI base units — the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
Pressure factors here come from fixed definitions, anchored to the pascal: a bar is exactly 100,000 Pa, one atmosphere is exactly 101,325 Pa, a torr is exactly a 760th of an atmosphere, and psi is built from the exact pound and the exact inch. Two of them — psi and the torr — work out to decimals that repeat forever, so where a number is shown rounded it is marked, not quietly trimmed.
Frequently asked questions
- How many pascal are in 1 millimetre of water?
- 1 millimetre of water = 9.80665 pascal (Pa). To convert any number of millimetre of water to pascal, multiply by 9.80665.
- How do I convert millimetre of water to pascal?
- Multiply the number of millimetre of water by 9.80665. For example, 10 millimetre of water = 10 × 9.80665 = 98.0665 pascal, and 25 millimetre of water = 245.1662 pascal.
- How many millimetre of water are in 1 pascal?
- 1 pascal = 0.1019716 millimetre of water. So to convert pascal back to millimetre of water, multiply by 0.1019716.
- What is the formula to convert millimetre of water to pascal?
- pascal = millimetre of water × 9.80665. The reverse formula is millimetre of water = pascal × 0.1019716.
- How much is 100 millimetre of water in pascal?
- 100 millimetre of water = 980.665 pascal. (And 1000 millimetre of water = 9,806.65 pascal.)
- Which is bigger, a millimetre of water or a pascal?
- A millimetre of water is larger: 1 millimetre of water = 9.80665 pascal.
- Is this millimetre of water to pascal converter accurate?
- Yes — every value is computed from the exact 9.80665 Pa per mmH₂O factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert pascal to millimetre of water too?
- Yes. The converter works both ways — enter a value in either field. 1 pascal = 0.1019716 millimetre of water.