To convert pounds per square foot to millitorr, multiply by 359.1314762. 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 unit US building codes give floor, roof and wind loads in. One thousandth of a torr, the working unit of vacuum deposition.
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 millitorr so the number you get has something to be compared against.
The formula
pounds per square foot- The amount you are converting, in pounds per square foot
359.131476191- The exact number of millitorr in one pound per square foot
millitorr- The converted result
How it works, step by step
- Enter the value in pounds per square foot.
- It is multiplied by 359.131476191, the exact factor between the two units.
- The answer is shown in millitorr, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A bicycle tyre: 1.3e+04 psf in millitorr
At 1.3e+04 psf (a bicycle tyre), the same quantity in millitorr is 1.3e+04 × 359.131 = 4.66871e+06 mTorr. One pound per square foot is 359.131 millitorr, so the numbers grow as expected.
A steam boiler: 2.09e+04 psf in millitorr
A steam boiler comes to about 2.09e+04 psf. Multiplying by the factor: 2.09e+04 × 359.131 = 7.50585e+06 mTorr. Dividing the answer back by 359.131 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 millitorr are in one pound per square foot?
Exactly 359.131476191. 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 pounds per square foot to millitorr?
millitorr = pounds per square foot × 359.131476191. Reversed, pounds per square foot = millitorr ÷ 359.131476191, which is the same as multiplying by 0.00278449555747.
Which is the bigger unit, the pound per square foot or the millitorr?
The pound per square foot. One pound per square foot equals 359.131 millitorr.
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 pound per square foot?
The unit US building codes give floor, roof and wind loads in.
What is a millitorr?
One thousandth of a torr, the working unit of vacuum deposition.
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 psf to mTorr in my head?
Plenty of people do this in their head: multiply by 360 instead of using the exact factor 359.1314762. At 100 that shortcut gives 36,000 millitorr, off by 86.85 millitorr or about 0.24%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Pounds Per Square Foot to millitorr reference tables
| Pounds Per Square Foot | Millitorr |
|---|---|
| 0.5 psf | 179.566 mTorr |
| 1 psf | 359.131 mTorr |
| 2 psf | 718.263 mTorr |
| 3 psf | 1077.39 mTorr |
| 5 psf | 1795.66 mTorr |
| 10 psf | 3591.31 mTorr |
| 20 psf | 7182.63 mTorr |
| 25 psf | 8978.29 mTorr |
| 50 psf | 17,956.6 mTorr |
| 75 psf | 26,934.9 mTorr |
| 100 psf | 35,913.1 mTorr |
| 250 psf | 89,782.9 mTorr |
| 500 psf | 179,566 mTorr |
| 1000 psf | 359,131 mTorr |
| 5000 psf | 1.79566e+06 mTorr |
Exact factor: 1 pound per square foot = 359.131476191 millitorr.
| Quantity | psf | mTorr |
|---|---|---|
| Sea-level air | 2116 psf | 7.6e+05 mTorr |
| A car tyre | 4608 psf | 1.655e+06 mTorr |
| Blood pressure, systolic | 334.1 psf | 1.2e+05 mTorr |
| A bicycle tyre | 1.296e+04 psf | 4.654e+06 mTorr |
| A domestic water main | 8354 psf | 3e+06 mTorr |
| A steam boiler | 2.089e+04 psf | 7.501e+06 mTorr |
Published reference values, converted with the same factor this page uses.