This page converts bar into inches of water using the factor 401.4630921, and shows the reverse figure alongside it. Both units measure pressure, which is why one number does the whole job.
Almost exactly atmospheric pressure; standard in European industry and diving. The low-pressure unit for duct static pressure and gas appliances in the US.
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 inches of water so the number you get has something to be compared against.
The formula
bar- The amount you are converting, in bar
401.463092093- The exact number of inches of water in one bar
inches of water- The converted result
How it works, step by step
- Enter the value in bar.
- It is multiplied by 401.463092093, the exact factor between the two units.
- The answer is shown in inches 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 inches of water
A steam boiler comes to about 10 bar. Multiplying by the factor: 10 × 401.463 = 4014.63 inH₂O. Dividing the answer back by 401.463 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
A car tyre: 2.21 bar in inches of water
A car tyre comes to about 2.21 bar. Multiplying by the factor: 2.21 × 401.463 = 887.233 inH₂O. Dividing the answer back by 401.463 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 inches of water are in one bar?
Exactly 401.463092093. 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 inches of water?
inches of water = bar × 401.463092093. Reversed, bar = inches of water ÷ 401.463092093, which is the same as multiplying by 0.002490889.
Which is the bigger unit, the bar or the inch of water?
The bar. One bar equals 401.463 inches 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 inch of water?
The low-pressure unit for duct static pressure and gas appliances in the US.
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 inH₂O in my head?
Plenty of people do this in their head: multiply by 400 instead of using the exact factor 401.4630921. At 100 that shortcut gives 40,000 inches of water, off by 146.3 inches of water or about 0.36%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Bar to inches of water reference tables
| Bar | Inches Of Water |
|---|---|
| 0.5 bar | 200.732 inH₂O |
| 1 bar | 401.463 inH₂O |
| 2 bar | 802.926 inH₂O |
| 3 bar | 1204.39 inH₂O |
| 5 bar | 2007.32 inH₂O |
| 10 bar | 4014.63 inH₂O |
| 20 bar | 8029.26 inH₂O |
| 25 bar | 10,036.6 inH₂O |
| 50 bar | 20,073.2 inH₂O |
| 75 bar | 30,109.7 inH₂O |
| 100 bar | 40,146.3 inH₂O |
| 250 bar | 100,366 inH₂O |
| 500 bar | 200,732 inH₂O |
| 1000 bar | 401,463 inH₂O |
| 5000 bar | 2.00732e+06 inH₂O |
Exact factor: 1 bar = 401.463092093 inches of water.
| Quantity | bar | inH₂O |
|---|---|---|
| Sea-level air | 1.013 bar | 406.8 inH₂O |
| A car tyre | 2.206 bar | 885.8 inH₂O |
| Blood pressure, systolic | 0.16 bar | 64.23 inH₂O |
| A bicycle tyre | 6.205 bar | 2491 inH₂O |
| A domestic water main | 4 bar | 1606 inH₂O |
| A steam boiler | 10 bar | 4015 inH₂O |
Published reference values, converted with the same factor this page uses.