To convert millibars to feet of water, multiply by 0.03345525656. That factor is the whole relationship: both units measure pressure, so the conversion is a proportion with no offset and no substance-specific constant.
The meteorologist’s unit — sea-level pressure averages 1013.25 mbar. Pump head expressed as a column of water — the way pump curves are drawn.
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. Two tables follow: rounded steps for quick lookup, and a set of real reference quantities converted into feet of water, which is usually more useful than the bare number.
The formula
millibars- The amount you are converting, in millibars
0.0334552565551- The exact number of feet of water in one millibar
feet of water- The converted result
How it works, step by step
- Enter the value in millibars.
- It is multiplied by 0.0334552565551, the exact factor between the two units.
- The answer is shown in feet of water, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
Sea-level air: 1010 mbar in feet of water
At 1010 mbar (sea-level air), the same quantity in feet of water is 1010 × 0.0334553 = 33.7898 ftH₂O. One millibar is 0.0334553 feet of water, so the numbers shrink as expected.
A steam boiler: 1e+04 mbar in feet of water
A steam boiler comes to about 1e+04 mbar. Multiplying by the factor: 1e+04 × 0.0334553 = 334.553 ftH₂O. Dividing the answer back by 0.0334553 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
How to read your score
Frequently asked questions
How many feet of water are in one millibar?
Exactly 0.0334552565551. 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 millibars to feet of water?
feet of water = millibars × 0.0334552565551. Reversed, millibars = feet of water ÷ 0.0334552565551, which is the same as multiplying by 29.890669.
Which is the bigger unit, the millibar or the foot of water?
The foot of water. One millibar is only 0.0334553 of a foot of water, so it takes 29.8907 millibars to make one foot 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 millibar?
The meteorologist’s unit — sea-level pressure averages 1013.25 mbar.
What is a foot of water?
Pump head expressed as a column of water — the way pump curves are drawn.
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 mbar to ftH₂O in my head?
Plenty of people do this in their head: divide by 30 instead of using the exact factor 0.03345525656. At 100 that shortcut gives 3.3333333 feet of water, off by 0.01219 feet of water or about 0.36%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Millibars to feet of water reference tables
| Millibars | Feet Of Water |
|---|---|
| 0.5 mbar | 0.0167276 ftH₂O |
| 1 mbar | 0.0334553 ftH₂O |
| 2 mbar | 0.0669105 ftH₂O |
| 3 mbar | 0.100366 ftH₂O |
| 5 mbar | 0.167276 ftH₂O |
| 10 mbar | 0.334553 ftH₂O |
| 20 mbar | 0.669105 ftH₂O |
| 25 mbar | 0.836381 ftH₂O |
| 50 mbar | 1.67276 ftH₂O |
| 75 mbar | 2.50914 ftH₂O |
| 100 mbar | 3.34553 ftH₂O |
| 250 mbar | 8.36381 ftH₂O |
| 500 mbar | 16.7276 ftH₂O |
| 1000 mbar | 33.4553 ftH₂O |
| 5000 mbar | 167.276 ftH₂O |
Exact factor: 1 millibar = 0.0334552565551 feet of water.
| Quantity | mbar | ftH₂O |
|---|---|---|
| Sea-level air | 1013 mbar | 33.9 ftH₂O |
| A car tyre | 2206 mbar | 73.81 ftH₂O |
| Blood pressure, systolic | 160 mbar | 5.352 ftH₂O |
| A bicycle tyre | 6205 mbar | 207.6 ftH₂O |
| A domestic water main | 4000 mbar | 133.8 ftH₂O |
| A steam boiler | 1e+04 mbar | 334.6 ftH₂O |
Published reference values, converted with the same factor this page uses.