This page converts atmospheres into millitorr using the factor 760,000, and shows the reverse figure alongside it. Both units measure pressure, which is why one number does the whole job.
One thousandth of a torr, the working unit of vacuum deposition. Standard atmospheric pressure by definition — 101,325 pascals exactly.
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
atmospheres- The amount you are converting, in atmospheres
760,000- The exact number of millitorr in one atmosphere
millitorr- The converted result
How it works, step by step
- Enter the value in atmospheres.
- It is multiplied by 760,000, 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
Blood pressure, systolic: 0.158 atm in millitorr
Take blood pressure, systolic, roughly 0.158 atm. The conversion is a single multiplication — 0.158 × 760,000 — giving 120,080 mTorr. Because the relationship is proportional, doubling the input doubles the answer to 240,160 mTorr.
Sea-level air: 1 atm in millitorr
Take sea-level air, roughly 1 atm. The conversion is a single multiplication — 1 × 760,000 — giving 760,000 mTorr. Because the relationship is proportional, doubling the input doubles the answer to 1.52e+06 mTorr.
How to read your score
Frequently asked questions
How many millitorr are in one atmosphere?
Exactly 760,000. 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 atmospheres to millitorr?
millitorr = atmospheres × 760,000. Reversed, atmospheres = millitorr ÷ 760,000, which is the same as multiplying by 1.31578947368e-06.
Which is the bigger unit, the atmosphere or the millitorr?
The atmosphere. One atmosphere equals 760,000 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 atmosphere?
Standard atmospheric pressure by definition — 101,325 pascals exactly.
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.
Atmospheres to millitorr reference tables
| Atmospheres | Millitorr |
|---|---|
| 0.5 atm | 380,000 mTorr |
| 1 atm | 760,000 mTorr |
| 2 atm | 1.52e+06 mTorr |
| 3 atm | 2.28e+06 mTorr |
| 5 atm | 3.8e+06 mTorr |
| 10 atm | 7.6e+06 mTorr |
| 20 atm | 1.52e+07 mTorr |
| 25 atm | 1.9e+07 mTorr |
| 50 atm | 3.8e+07 mTorr |
| 75 atm | 5.7e+07 mTorr |
| 100 atm | 7.6e+07 mTorr |
| 250 atm | 1.9e+08 mTorr |
| 500 atm | 3.8e+08 mTorr |
| 1000 atm | 7.6e+08 mTorr |
| 5000 atm | 3.8e+09 mTorr |
Exact factor: 1 atmosphere = 760,000 millitorr.
| Quantity | atm | mTorr |
|---|---|---|
| Sea-level air | 1 atm | 7.6e+05 mTorr |
| A car tyre | 2.177 atm | 1.655e+06 mTorr |
| Blood pressure, systolic | 0.1579 atm | 1.2e+05 mTorr |
| A bicycle tyre | 6.124 atm | 4.654e+06 mTorr |
| A domestic water main | 3.948 atm | 3e+06 mTorr |
| A steam boiler | 9.869 atm | 7.501e+06 mTorr |
Published reference values, converted with the same factor this page uses.