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Vacuum Converter (mbar, microns, torr)

Type a value — the result and every other unit update as you type.

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Understanding the vacuum pressure converter — concept and principle

Vacuum work uses its own pressure units. Air-conditioning and refrigeration technicians read microns of mercury on their gauges, laboratory and coating equipment is labelled in millibar or torr, and scientific papers use pascals. This converter changes a vacuum reading between microns (mTorr), torr, Pa, mbar/hPa, inches of mercury and standard atmospheres, so you can follow a manual written in one system with a gauge that shows another.

500 microns compared with the atmosphereAir at 1 atm is about 760,000 microns; at 500 microns less than 0.07 % of it remains. 500 microns = 0.5 torr = 66.66 Pa = 0.6666 mbar.500 microns: nearly all the air is goneair 1 atm≈ 760,000 microns500 microns< 0.07 % leftpump500 microns (mTorr) equals0.5torr66.66Pa0.6666mbar1 micron = 1 mTorr ≈ 0.1333 Pa
A lower number means a deeper vacuum. The dots only hint at the idea; a real jar at 500 microns still holds countless molecules.

How it is calculated

All units are stored in millibar, then rescaled: result = value × mbar(from) ÷ mbar(to).

The principle

A vacuum is just a pressure below atmospheric, and every unit here measures absolute pressure, the force per area exerted by the remaining gas. The torr was defined as 1/760 of a standard atmosphere, matching the old idea of a mercury column 760 mm tall, so 1 torr is almost exactly 1 mmHg. A micron is one thousandth of that: a mercury column one micrometre high. Pascals are the SI unit (newton per square metre), and the millibar is 100 Pa, the same size as the hectopascal used in weather maps. Because these units span many orders of magnitude, vacuum levels are often described by range: ISO 3529-1 calls 100 kPa to 100 Pa low (rough) vacuum and 100 Pa to 0.1 Pa medium vacuum.

Worked example

Default inputs: 500 microns to pascals.

  1. 500 microns = 500 mTorr = 0.5 torr.
  2. 0.5 × 133.3224 Pa = 66.66118421 Pa.
  3. Ratio check: 1 micron = 0.1333223684 Pa.
  4. Other units: 0.6666118421 mbar, 0.0196850345 inHg, 0.0006578947 atm.

How to read the result

Lower numbers mean a deeper vacuum. Atmospheric pressure is about 760,000 microns, so 500 microns leaves less than 0.07 % of the original air. That level falls in the medium-vacuum range and is a common evacuation target in refrigeration service, though you should follow the equipment maker's procedure. Rough pumps and lab work often quote mbar; high-vacuum work uses 10⁻³ Pa and below, usually written in scientific notation.

Common mistakes

Keep in mind: Conversions are exact, but gauge readings depend on gas type, sensor type and calibration. Follow manufacturer procedures and refrigerant handling rules, and use qualified technicians for regulated work.

Frequently asked questions

How many microns is 1 torr?

1,000 microns.

What is 500 microns in Pa?

About 66.66 Pa, or 0.667 mbar.

Is torr the same as mmHg?

Practically yes; they differ by less than one part in a million.

Sources: BIPM, The International System of Units (SI Brochure), 9th edition, 2019 · NIST Special Publication 811 (2008), Guide for the Use of the SI, Appendix B · ISO 3529-1, Vacuum technology — Vocabulary — Part 1: General terms

Checked 8 Nov 2026. Factors from the SI Brochure (BIPM, 9th ed.) and NIST Special Publication 811 (2008), Appendix B.

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