To convert millimeters of mercury to pounds per square foot, multiply by 2.784495954. 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. The clinical unit for blood pressure worldwide.
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 pounds per square foot, which is usually more useful than the bare number.
The formula
millimeters of mercury- The amount you are converting, in millimeters of mercury
2.78449595416- The exact number of pounds per square foot in one millimeter of mercury
pounds per square foot- The converted result
How it works, step by step
- Enter the value in millimeters of mercury.
- It is multiplied by 2.78449595416, the exact factor between the two units.
- The answer is shown in pounds per square foot, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A domestic water main: 3000 mmHg in pounds per square foot
A domestic water main comes to about 3000 mmHg. Multiplying by the factor: 3000 × 2.7845 = 8353.49 psf. Dividing the answer back by 2.7845 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
Blood pressure, systolic: 120 mmHg in pounds per square foot
Blood pressure, systolic comes to about 120 mmHg. Multiplying by the factor: 120 × 2.7845 = 334.14 psf. Dividing the answer back by 2.7845 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 pounds per square foot are in one millimeter of mercury?
Exactly 2.78449595416. 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 millimeters of mercury to pounds per square foot?
pounds per square foot = millimeters of mercury × 2.78449595416. Reversed, millimeters of mercury = pounds per square foot ÷ 2.78449595416, which is the same as multiplying by 0.359131425027.
Which is the bigger unit, the millimeter of mercury or the pound per square foot?
The millimeter of mercury. One millimeter of mercury equals 2.7845 pounds per square foot.
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 millimeter of mercury?
The clinical unit for blood pressure worldwide.
What is a pound per square foot?
The unit US building codes give floor, roof and wind loads 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 mmHg to psf in my head?
Plenty of people do this in their head: multiply by 2.8 instead of using the exact factor 2.784495954. At 100 that shortcut gives 280 pounds per square foot, off by 1.55 pounds per square foot or about 0.56%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Millimeters Of Mercury to pounds per square foot reference tables
| Millimeters Of Mercury | Pounds Per Square Foot |
|---|---|
| 0.5 mmHg | 1.39225 psf |
| 1 mmHg | 2.7845 psf |
| 2 mmHg | 5.56899 psf |
| 3 mmHg | 8.35349 psf |
| 5 mmHg | 13.9225 psf |
| 10 mmHg | 27.845 psf |
| 20 mmHg | 55.6899 psf |
| 25 mmHg | 69.6124 psf |
| 50 mmHg | 139.225 psf |
| 75 mmHg | 208.837 psf |
| 100 mmHg | 278.45 psf |
| 250 mmHg | 696.124 psf |
| 500 mmHg | 1392.25 psf |
| 1000 mmHg | 2784.5 psf |
| 5000 mmHg | 13,922.5 psf |
Exact factor: 1 millimeter of mercury = 2.78449595416 pounds per square foot.
| Quantity | mmHg | psf |
|---|---|---|
| Sea-level air | 760 mmHg | 2116 psf |
| A car tyre | 1655 mmHg | 4608 psf |
| Blood pressure, systolic | 120 mmHg | 334.1 psf |
| A bicycle tyre | 4654 mmHg | 1.296e+04 psf |
| A domestic water main | 3000 mmHg | 8354 psf |
| A steam boiler | 7501 mmHg | 2.089e+04 psf |
Published reference values, converted with the same factor this page uses.