In 1 millitorr there are 0.00000131579 atmospheres. Meanwhile in 1 atmospheres there are 760,000 millitorr. Keep reading to learn more about each unit of measure and how they are calculated. Or just use the Atmospheres to Millitorr calculator above to convert any number.
* Values rounded to 6 decimal places for readability
To convert millitorr (mTorr) to atmospheres (atm), use the fact that 1 atm = 760 Torr and 1 Torr = 1,000 mTorr. That means 1 atm = 760,000 mTorr.
Conversion formula (mTorr to atm):
Steps:
Example conversions:
Tip: For quick estimates, remember 1 mTorr = 0.00000000131579 atm (about 1.316 × 10⁻⁹ atm).
A millitorr is a small unit of pressure. It equals one-thousandth of a torr (0.001 Torr). People often use mTorr for vacuum and low-pressure work, like lab chambers and thin-film tools.
An atmosphere is a standard unit of pressure based on average sea-level air pressure. It’s used in physics, chemistry, and engineering. One standard atmosphere is close to everyday air pressure at sea level.
Use this conversion factor:
1 atm = 760 Torr = 760,000 mTorr
So the formula is:
atm = mTorr ÷ 760,000
The direct factor is:
1 mTorr = 1 / 760,000 atm
That is 1 mTorr ≈ 0.00000131579 atm.
1 mTorr ≈ 0.00000131579 atm.
That’s about 1.32 micro-atm.
1 atm = 760,000 mTorr.
This is a common reference point for vacuum readings.
Divide by 760,000:
Here are a few quick values:
A torr is defined as 1/760 of an atmosphere. Since 1 mTorr is 1/1000 of a torr, you multiply 760 by 1000. That gives 760,000 mTorr per atm.
They’re close in many real-world cases, but they are not exactly the same. Torr is defined from an atmosphere (1 atm = 760 Torr). mmHg is based on a mercury column and can differ slightly by definition. In most lab work, people treat them as equal for quick conversions.
No. Converting mTorr to atm is a unit change, so temperature doesn’t enter the math. Temperature matters when pressure links to gas behavior, like in the ideal gas law.
Keep the key facts in mind:
It helps when you want to compare vacuum pressure to standard air pressure. It’s also helpful when equations or specs use atm, but your gauge reads in mTorr.
The Calculate Box tool to convert millitorr to atmospheres uses the open source script Convert.js to convert units of measurement. To use this tool, simply type a millitorr value in the box and have it instantly converted to atmospheres.