This page converts bar into centimeters of water using the factor 1019.716213, 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. Below the calculator there is a step table for the values people look up most, and a second table putting real pressure figures into centimeters of water so the number you get has something to be compared against.
The formula
bar- The amount you are converting, in bar
1019.71621298- The exact number of centimeters of water in one bar
centimeters of water- The converted result
How it works, step by step
- Enter the value in bar.
- It is multiplied by 1019.71621298, the exact factor between the two units.
- The answer is shown in centimeters of water, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A steam boiler: 10 bar in centimeters of water
At 10 bar (a steam boiler), the same quantity in centimeters of water is 10 × 1019.72 = 10,197.2 cmH₂O. One bar is 1019.72 centimeters of water, so the numbers grow as expected.
A car tyre: 2.21 bar in centimeters of water
Take a car tyre, roughly 2.21 bar. The conversion is a single multiplication — 2.21 × 1019.72 — giving 2253.57 cmH₂O. Because the relationship is proportional, doubling the input doubles the answer to 4507.15 cmH₂O.
How to read your score
Frequently asked questions
How many centimeters of water are in one bar?
Exactly 1019.71621298. 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 bar to centimeters of water?
centimeters of water = bar × 1019.71621298. Reversed, bar = centimeters of water ÷ 1019.71621298, which is the same as multiplying by 0.000980665.
Which is the bigger unit, the bar or the centimeter of water?
The bar. One bar equals 1019.72 centimeters of water.
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 bar?
Almost exactly atmospheric pressure; standard in European industry and diving.
What is a centimeter of water?
The unit ventilator and CPAP pressures are set in.
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 bar to cmH₂O in my head?
Plenty of people do this in their head: multiply by 1000 instead of using the exact factor 1019.716213. At 100 that shortcut gives 100,000 centimeters of water, off by 1972 centimeters of water or about 1.93%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Bar to centimeters of water reference tables
| Bar | Centimeters Of Water |
|---|---|
| 0.5 bar | 509.858 cmH₂O |
| 1 bar | 1019.72 cmH₂O |
| 2 bar | 2039.43 cmH₂O |
| 3 bar | 3059.15 cmH₂O |
| 5 bar | 5098.58 cmH₂O |
| 10 bar | 10,197.2 cmH₂O |
| 20 bar | 20,394.3 cmH₂O |
| 25 bar | 25,492.9 cmH₂O |
| 50 bar | 50,985.8 cmH₂O |
| 75 bar | 76,478.7 cmH₂O |
| 100 bar | 101,972 cmH₂O |
| 250 bar | 254,929 cmH₂O |
| 500 bar | 509,858 cmH₂O |
| 1000 bar | 1.01972e+06 cmH₂O |
| 5000 bar | 5.09858e+06 cmH₂O |
Exact factor: 1 bar = 1019.71621298 centimeters of water.
| Quantity | bar | cmH₂O |
|---|---|---|
| Sea-level air | 1.013 bar | 1033 cmH₂O |
| A car tyre | 2.206 bar | 2250 cmH₂O |
| Blood pressure, systolic | 0.16 bar | 163.1 cmH₂O |
| A bicycle tyre | 6.205 bar | 6328 cmH₂O |
| A domestic water main | 4 bar | 4079 cmH₂O |
| A steam boiler | 10 bar | 1.02e+04 cmH₂O |
Published reference values, converted with the same factor this page uses.