Are torr and mmHg the same unit?

Almost, but not exactly. 1 torr is exactly 1/760 of a standard atmosphere, or about 133.322368421 Pa. Conventional mmHg is 133.322387415 Pa. Therefore 1 torr is about 0.9999998575 mmHg, a difference of roughly 0.0000142%.

How do I convert torr to mmHg manually?

Multiply torr by 0.9999998575. For example, 760 torr is approximately 759.999892 mmHg; in everyday use this rounds to 760 mmHg.

How do I convert mmHg to torr?

Divide mmHg by 0.9999998575, or multiply by approximately 1.0000001425. For example, 760 mmHg is approximately 760.000108 torr.

Where is the torr unit used?

The torr is used widely in vacuum science, semiconductor fabrication, mass spectrometry, and gas chromatography. It is particularly common in English-language vacuum engineering literature. The mmHg unit is more common in medical contexts (blood pressure) and older meteorology.

What is standard atmospheric pressure in torr and mmHg?

Standard atmospheric pressure is exactly 760 torr and approximately 759.999892 conventional mmHg (≈ 760 mmHg in practice).

Does this converter handle negative or very small pressures?

Yes. You can enter any non-negative decimal value, including very small ones like 0.001 torr (common in high vacuum work). The tool will display the result in standard or scientific notation as appropriate.

Torr to mmHg Converter

Enter a pressure in torr and get the mmHg equivalent — with the reverse direction and a note on why the two units differ by 0.0000142%.

Converter

Pressure in torr

Result in mmHg

Reverse: mmHg to torr

Pressure in mmHg

Result in torr

Why the two units differ: The torr is exactly 1/760 atm. Conventional mmHg uses 133.322387415 Pa. The ratio is 1 torr ≈ 0.9999998575 mmHg — a 0.0000142% gap that matters only in high-precision calibration.

Reference Table

Torr mmHg

0.001 torr 0.000999999858 mmHg

0.01 torr 0.009999998575 mmHg

0.1 torr 0.09999998575 mmHg

1 torr 0.9999998575 mmHg

10 torr 9.999998575 mmHg

100 torr 99.99998575 mmHg

760 torr 759.9998917 mmHg

1,000 torr 999.9998575 mmHg

10,000 torr 9,999.998575 mmHg

100,000 torr 99,999.98575 mmHg

Summary

Torr and millimeters of mercury (mmHg) are so close in value that most instruments treat them as identical, yet they are defined differently: the torr is exactly 1/760 of a standard atmosphere, while conventional mmHg is based on 133.322387415 Pa. The ratio is 1 torr ≈ 0.9999998575 mmHg — a difference of about 0.0000142%. This converter applies the high-precision factor in both directions and includes common reference values.

How it works

Enter a pressure value in torr in the input field.
The converter multiplies by 0.9999998575 to get the equivalent in mmHg.
The result updates instantly as you type.
Use the reverse field to convert mmHg back to torr (divides by 0.9999998575).
Click "Copy" next to any result to copy it to the clipboard.
Check the reference table for common torr-to-mmHg values.

Use cases

Express vacuum pump specifications precisely when documentation distinguishes torr from mmHg.
Convert blood pressure readings between mmHg and torr for scientific publications.
Validate barometric pressure conversions in meteorology software.
Check whether a measurement tool calibrated in torr is within spec when compared to an mmHg reference.
Translate gas chromatography carrier pressures between lab instruments using different unit conventions.
Clarify the torr/mmHg distinction in lab reports and vacuum engineering datasheets.

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu