Comprehensive Vacuum Conversion Chart for Engineering and Industrial Use
Comprehensive Vacuum Conversion Chart for Engineering and Industrial Use
Introduction
Understanding vacuum pressure units is crucial in fields ranging from industrial automation to laboratory science. Engineers, technicians, and researchers often work with a wide variety of pressure units—Pascal (Pa), Torr, millibar (mbar), psi, and more—depending on the system, region, or application. This guide presents a comprehensive vacuum conversion chart tailored for real-world use. It enables quick reference across units and percent vacuum levels, helping ensure proper calibration, system design, and troubleshooting. Whether you’re working with suction cups, vacuum pumps, or pressure sensors, this resource simplifies cross-unit understanding and eliminates guesswork in converting vacuum values.
Vacuum Conversion Table
Purpose
This vacuum conversion chart is a valuable tool for instantly finding the absolute pressure corresponding to a set percentage vacuum level. It helps engineers and designers visualize how much air has been removed from a system, based on ambient atmospheric pressure as the baseline. The table enables fast and accurate conversion between % vacuum and corresponding values in Torr, micron, psia, inHg (absolute), and kilopascal (kPa abs).
This is especially useful in calculating system efficiency, sizing vacuum generators, or specifying components like suction cups and sensors. By referencing this chart, users can better align equipment design with the pressure conditions of their actual application environment.
For Practical/Operational Use
This chart is widely used in vacuum handling operations, where suction performance and holding force vary by vacuum level. Factory personnel rely on it to calibrate suction cups, adjust vacuum generators, and ensure system stability during operation.
Maintenance engineers also consult this table to assess whether a vacuum system is achieving its target pressure range, especially in situations where gauge readings can be misleading or vary due to altitude and atmospheric changes. In industrial settings, understanding the relationship between vacuum percentage and pressure units is key to avoiding performance losses and ensuring consistent product quality.
Vacuum Conversion Chart
| % Vacuum | Torr (mm Hg) | Micron | psia (lb/in² abs) | Inches Mercury Absolute | Inches Mercury Gauge | kPa abs |
| 0.0 | 760.0 | 760,000 | 14.7 | 29.92 | 0.00 | 101.4 |
| 1.3 | 750.0 | 750,000 | 14.5 | 29.5 | 0.42 | 99.9 |
| 1.9 | 735.6 | 735,600 | 14.2 | 28.9 | 1.02 | 97.7 |
| 7.9 | 700.0 | 700,000 | 13.5 | 27.6 | 2.32 | 93.5 |
| 21.0 | 600.0 | 600,000 | 11.6 | 23.6 | 6.32 | 79.9 |
| 34.0 | 500.0 | 500,000 | 9.7 | 19.7 | 10.22 | 66.7 |
| 47.0 | 400.0 | 400,000 | 7.7 | 15.7 | 14.22 | 53.2 |
| 50.0 | 380.0 | 380,000 | 7.3 | 15.0 | 14.92 | 50.8 |
| 61.0 | 300.0 | 300,000 | 5.8 | 11.8 | 18.12 | 40.0 |
| 74.0 | 200.0 | 200,000 | 3.9 | 7.85 | 22.07 | 26.6 |
| 87.0 | 100.0 | 100,000 | 1.93 | 3.94 | 25.98 | 13.3 |
| 88.0 | 90.0 | 90,000 | 1.74 | 3.54 | 26.38 | 12.0 |
| 89.5 | 80.0 | 80,000 | 1.55 | 3.15 | 26.77 | 10.7 |
| 90.8 | 70.0 | 70,000 | 1.35 | 2.76 | 27.16 | 9.3 |
| 92.1 | 60.0 | 60,000 | 1.16 | 2.36 | 27.56 | 8.0 |
| 93.0 | 51.7 | 51,700 | 1.00 | 2.03 | 27.89 | 6.9 |
| 93.5 | 50.0 | 50,000 | 0.97 | 1.97 | 27.95 | 6.7 |
| 94.8 | 40.0 | 40,000 | 0.77 | 1.57 | 28.35 | 5.3 |
| 96.1 | 30.0 | 30,000 | 0.58 | 1.18 | 28.74 | 4.0 |
| 96.6 | 25.4 | 25,400 | 0.49 | 1.00 | 28.92 | 3.4 |
| 97.4 | 20.0 | 20,000 | 0.39 | 0.785 | 29.14 | 2.7 |
| 98.7 | 10.0 | 10,000 | 0.193 | 0.394 | 29.53 | 1.3 |
| 99.0 | 7.6 | 7,600 | 0.147 | 0.299 | 29.62 | 1.0 |
| 99.87 | 1.0 | 1,000 | 0.01934 | 0.03937 | 29.88 | 0.13 |
| 99.90 | 0.75 | 750 | 0.0145 | 0.0295 | 29.89 | 0.1 |
| 99.99 | 0.10 | 100 | 0.00193 | 0.00394 | 29.916 | 0.013 |
| 99.999 | 0.01 | 10 | 0.000193 | 0.000394 | 29.9196 | 0.0013 |
| 100 | 0.00 | 0 | 0 | 0.00 | 29.92 | 0 |
Note: This chart converts percentage vacuum into absolute pressure units, making it ideal for configuring vacuum systems in manufacturing, packaging, laboratory testing, and field service environments.
Common Vacuum Pressure Units
Key Units Explained
- Pascal (Pa) – The SI unit of pressure, widely used in scientific and engineering documentation. 1 Pascal = 1 Newton per square meter.
- Millibar (mbar) / Hectopascal (hPa) – Metric units used often in meteorology and vacuum packaging. 1 mbar = 100 Pa.
- Torr / mmHg – Common in laboratory and vacuum gauge usage. 1 Torr = 1 mmHg = 133.322 Pa.
- inHg (Inches of Mercury) – Used in the imperial system, particularly in North America for HVAC and automotive applications. 1 inHg = 3386 Pa.
- psi (Pounds per Square Inch) – Popular in U.S. industrial settings. 1 psi = 6.895 kPa = 6,895 Pa.
- atm / at (Atmospheres) – Refer to atmospheric pressure. 1 atm = 101.325 kPa; 1 technical atmosphere (at) = 98.067 kPa.
Understanding Absolute, Relative, and Percentage Vacuum
To avoid confusion, it’s critical to distinguish between absolute pressure, gauge pressure, and percentage vacuum:
- Absolute Pressure (abs): The total pressure measured from a perfect vacuum (0 Pa). Always positive.
- Gauge Pressure: Measures pressure relative to the local atmospheric pressure. Can read negative when below ambient.
- Percentage Vacuum: Expresses how much pressure has been removed from a system compared to atmospheric pressure.
Clarifying Common Misinterpretations
A common mistake is misreading negative gauge pressures as true vacuums. For example:
“-600 mbar” is not absolute vacuum—it means the pressure is 600 mbar below ambient (atmospheric pressure), not 600 mbar absolute. If atmospheric pressure is 1000 mbar, then the actual absolute pressure is 400 mbar.
Similarly, a “60% vacuum” implies 60% of atmospheric pressure has been removed. At sea level (~1000 mbar), this means the absolute pressure is around 400 mbar.
Understanding these distinctions is vital when:
- Calibrating sensors
- Setting vacuum switches
- Reading mechanical vacuum gauges accurately
Standard Vacuum Pressure Unit Conversions
Vacuum Pressure Unit Conversion Table
| Pressure Unit | Equivalent in Pascal (Pa) | Notes |
| 1 bar | 100,000 Pa | Often used in European engineering systems |
| 1 millibar (mbar) | 100 Pa | Common in vacuum packaging, meteorology |
| 1 hectopascal (hPa) | 100 Pa | Identical to mbar, often used in weather reports |
| 1 atm (standard) | 101,325 Pa | Atmospheric pressure at sea level |
| 1 at (technical atm) | 98,067 Pa | Slightly lower than physical atmosphere |
| 1 Torr | 133.322 Pa | Used in vacuum gauges and scientific research |
| 1 mmHg | 133.322 Pa | Equivalent to Torr; based on mercury column |
| 1 psi | 6,894.76 Pa | Common in U.S. industrial equipment |
| 1 inHg (0°C) | 3,386.39 Pa | Used in HVAC and auto industries |
| 1 micron (µm) | 0.133322 Pa | Ultra-low vacuum measurement; 1 micron = 1/1000 Torr |
Purpose
This table provides a standard reference for converting widely used vacuum pressure units into Pascal (Pa)—the SI base unit of pressure. Such conversions are essential for ensuring accuracy in system calibration, consistent documentation across international projects, and compatibility in simulation software and automation systems.
By unifying all units under a common baseline (Pa), engineers and technicians can prevent misinterpretation, avoid costly system mismatches, and ensure cross-border communication of specifications is error-free.
For Practical/Operational Use
Professionals use this conversion table in a wide range of contexts:
- Engineering design of vacuum systems requiring SI-compliant inputs
- Research laboratories conducting experiments where precision and unit uniformity are mandatory
- Cross-national equipment calibration, especially when suppliers and clients use different unit standards
- Comparing vacuum pump or sensor specs from manufacturers listing data in psi, bar, or Torr
How to Use This Vacuum Conversion Chart
- Identify the Original Unit
Start by locating the unit you’re working with—such as psi, inHg, Torr, or micron. Refer to the Standard Unit Conversion Table for the corresponding value in Pascal (Pa). - Use the Conversion Factor
Multiply your original value by the listed conversion factor to get the pressure in Pascal. For instance:- 1 bar = 100,000 Pa
- 1 Torr = 133.322 Pa
- 1 psi = 6,894.76 Pa
- 1 inHg = 3,386.39 Pa
- Apply to Your System
Use the Pascal value in:- Vacuum controller input fields
- Sensor calibration
- Cross-checking supplier specs
- Design simulations requiring SI units
- Example Calculation
Suppose a vacuum gauge reads 23 inHg (absolute). To convert to Pa:
→ 23 × 3,386.39 = 77,885 Pa