Are torr and mmHg the same unit?

Almost, but not exactly. 1 torr is defined as exactly 1/760 of a standard atmosphere (101,325 Pa). 1 mmHg is defined by the physical pressure exerted by a 1 mm column of mercury at 0 °C under standard gravity (9.80665 m/s²), which equals 133.322387415 Pa. The ratio is 1 torr = 1.000000142 mmHg — a difference of about 0.0000142%. For most practical purposes the units are interchangeable, but high-precision calibration work may require the exact factor.

How do I convert torr to mmHg manually?

Multiply the torr value by 1.000000142. For example, 760 torr × 1.000000142 ≈ 760.000108 mmHg. In everyday use this rounds to 760 mmHg, which is why the units are often treated as identical.

How do I convert mmHg to torr?

Divide the mmHg value by 1.000000142, or equivalently multiply by 0.999999858. For example, 760 mmHg / 1.000000142 ≈ 759.999892 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 760.000108 mmHg (≈ 760 mmHg in practice). Both units were historically tied to the height of a mercury column under standard conditions, which is why they are so close.

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

Name: Torr to mmHg Converter
Availability: InStock
Author: Nham Vu

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 defined as 1/760 atm (exact). The mmHg is defined by a physical mercury column at 0 °C under standard gravity. The ratio is 1 torr = 1.000000142 mmHg — a 0.0000142% gap that matters only in high-precision calibration.

Reference Table

Torr mmHg

0.001 torr 0.001000000142 mmHg

0.01 torr 0.01000000142 mmHg

0.1 torr 0.1000000142 mmHg

1 torr 1.000000142 mmHg

10 torr 10.00000142 mmHg

100 torr 100.0000142 mmHg

760 torr 760.0001079 mmHg

1,000 torr 1,000.000142 mmHg

10,000 torr 10,000.00142 mmHg

100,000 torr 100,000.0142 mmHg

Summary

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%.

How it works

Enter a pressure value in torr in the input field.
The converter multiplies by 1.000000142 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 1.000000142).
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: 2026-07-23 · Reviewed by Nham Vu