This page converts centimeters of water into bar using the factor 0.000980665, and shows the reverse figure alongside it. Both units measure pressure, which is why one number does the whole job.
The unit ventilator and CPAP pressures are set in. Almost exactly atmospheric pressure; standard in European industry and diving.
Gauge versus absolute. A tyre gauge reading 32 psi means 32 psi above atmospheric, which is about 46.7 psi absolute. Converting the number is straightforward; remembering which zero it was measured from is where the mistakes happen. N/mm² and MPa are the same size, so a drawing quoting either is quoting the same stress. The tables underneath give both a plain step-by-step lookup and a list of real quantities expressed in bar, so you can sanity-check whether your answer is a plausible size.
The formula
centimeters of water- The amount you are converting, in centimeters of water
0.000980665- The exact number of bar in one centimeter of water
bar- The converted result
How it works, step by step
- Enter the value in centimeters of water.
- It is multiplied by 0.000980665, the exact factor between the two units.
- The answer is shown in bar, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A steam boiler: 1.02e+04 cmH₂O in bar
Take a steam boiler, roughly 1.02e+04 cmH₂O. The conversion is a single multiplication — 1.02e+04 × 0.000980665 — giving 10.0028 bar. Because the relationship is proportional, doubling the input doubles the answer to 20.0056 bar.
A domestic water main: 4080 cmH₂O in bar
At 4080 cmH₂O (a domestic water main), the same quantity in bar is 4080 × 0.000980665 = 4.00111 bar. One centimeter of water is 0.000980665 bar, so the numbers shrink as expected.
How to read your score
Frequently asked questions
How many bar are in one centimeter of water?
Exactly 0.000980665. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert centimeters of water to bar?
bar = centimeters of water × 0.000980665. Reversed, centimeters of water = bar ÷ 0.000980665, which is the same as multiplying by 1019.71621298.
Which is the bigger unit, the centimeter of water or the bar?
The bar. One centimeter of water is only 0.000980665 of a bar, so it takes 1019.72 centimeters of water to make one bar.
What does this quantity actually measure?
Both units measure pressure. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a centimeter of water?
The unit ventilator and CPAP pressures are set in.
What is a bar?
Almost exactly atmospheric pressure; standard in European industry and diving.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do cmH₂O to bar in my head?
Plenty of people do this in their head: divide by 1000 instead of using the exact factor 0.000980665. At 100 that shortcut gives 0.1 bar, off by 0.001933 bar or about 1.97%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Centimeters Of Water to bar reference tables
| Centimeters Of Water | Bar |
|---|---|
| 0.5 cmH₂O | 0.000490333 bar |
| 1 cmH₂O | 0.000980665 bar |
| 2 cmH₂O | 0.00196133 bar |
| 3 cmH₂O | 0.002942 bar |
| 5 cmH₂O | 0.00490333 bar |
| 10 cmH₂O | 0.00980665 bar |
| 20 cmH₂O | 0.0196133 bar |
| 25 cmH₂O | 0.0245166 bar |
| 50 cmH₂O | 0.0490333 bar |
| 75 cmH₂O | 0.0735499 bar |
| 100 cmH₂O | 0.0980665 bar |
| 250 cmH₂O | 0.245166 bar |
| 500 cmH₂O | 0.490333 bar |
| 1000 cmH₂O | 0.980665 bar |
| 5000 cmH₂O | 4.90333 bar |
Exact factor: 1 centimeter of water = 0.000980665 bar.
| Quantity | cmH₂O | bar |
|---|---|---|
| Sea-level air | 1033 cmH₂O | 1.013 bar |
| A car tyre | 2250 cmH₂O | 2.206 bar |
| Blood pressure, systolic | 163.1 cmH₂O | 0.16 bar |
| A bicycle tyre | 6328 cmH₂O | 6.205 bar |
| A domestic water main | 4079 cmH₂O | 4 bar |
| A steam boiler | 1.02e+04 cmH₂O | 10 bar |
Published reference values, converted with the same factor this page uses.