Bar to mmHg Converter
Accurate pressure conversion between bar and millimeters of mercury
Conversion Result
Quick Conversions
Conversion Formula & Steps
Formula
This conversion uses the standard relationship where 1 bar equals 750.062 mmHg at 0°C.
Conversion Steps
- Identify your pressure value in bar
- Multiply the bar value by 750.062
- The result is your pressure in mmHg
- Round to desired decimal places if needed
3 × 750.062 = 2,250.186 mmHg
Common Conversion Table
| Bar (bar) | Millimeters of Mercury (mmHg) |
|---|---|
| 0.1 | 75.006 |
| 0.5 | 375.031 |
| 1 | 750.062 |
| 1.5 | 1,125.093 |
| 2 | 1,500.124 |
| 3 | 2,250.186 |
| 4 | 3,000.248 |
| 5 | 3,750.310 |
| 6 | 4,500.372 |
| 7 | 5,250.434 |
| 8 | 6,000.496 |
| 9 | 6,750.558 |
| 10 | 7,500.620 |
| 15 | 11,250.930 |
| 20 | 15,001.240 |
Pressure Unit Comparison
1 Bar
1 Bar
1 Bar
1 mmHg
Real-World Applications
Medical Field
Blood pressure measurements traditionally use mmHg as the standard unit. Hyperbaric oxygen therapy chambers, however, often display pressure in bar. Converting between these units ensures accurate medical equipment calibration and patient safety during treatments.
Industrial Equipment
Hydraulic systems, pneumatic machinery, and pressure vessels commonly operate in the bar range (1-10 bar). Quality control procedures may require mmHg readings for precision testing, particularly in vacuum systems where measurements below atmospheric pressure are critical.
Scientific Research
Laboratory vacuum pumps and controlled atmosphere chambers require precise pressure monitoring. Researchers converting between bar and mmHg maintain consistency when comparing results with historical data, which often uses mmHg for torr measurements.
Automotive Industry
Tire pressure gauges in Europe typically display bar (2-3 bar for passenger vehicles), while some diagnostic equipment uses mmHg. Brake system testing and engine manifold pressure readings may require conversions between these units for accurate diagnostics.
About Pressure Units
Bar
The bar is a metric unit of pressure defined as 100,000 pascals. It approximates atmospheric pressure on Earth at sea level. The name derives from the Greek word “báros” meaning weight. Engineers and meteorologists widely adopt this unit because it provides convenient values for typical working pressures without requiring large numbers or small decimals.
Millimeters of Mercury (mmHg)
The mmHg unit represents the pressure exerted by a 1-millimeter-high column of mercury at 0°C under standard gravity (9.80665 m/s²). Evangelista Torricelli invented the mercury barometer in 1643, establishing this measurement method. Medical professionals prefer mmHg for blood pressure readings due to its historical precedence and appropriate scale (typical human blood pressure ranges from 60-180 mmHg).
Relationship Between Units
Both units measure pressure but originated from different contexts. Bar emerged from the metric system for industrial applications, while mmHg evolved from early barometric instruments. One bar equals exactly 750.062 mmHg at standard conditions. The slight difference from 750 occurs because atmospheric pressure (1 atm = 760 mmHg) differs from 1 bar (1 bar = 0.98692 atm).
Frequently Asked Questions
Multiply your bar value by 750.062 to get mmHg. For example, 2 bar × 750.062 = 1,500.124 mmHg. This conversion factor derives from the definitions of both units relative to the pascal (SI pressure unit).
The difference arises because 1 bar (100,000 Pa) and standard atmospheric pressure (101,325 Pa = 760 mmHg) are not identical. When you calculate 1 bar using the precise definition of mmHg (133.322 Pa), you get 100,000 ÷ 133.322 = 750.062 mmHg.
Yes, for practical purposes mmHg and torr are equivalent. Both represent the pressure exerted by 1 mm of mercury. The torr was named after Evangelista Torricelli and is defined as exactly 1/760 of standard atmospheric pressure, making it nearly identical to mmHg.
Bar is prevalent in automotive (tire pressure), meteorology (atmospheric pressure), and industrial engineering (hydraulic systems). mmHg dominates in medical applications (blood pressure, respiratory measurements) and scientific laboratories (vacuum systems, gas pressure in experiments).
Standard atmospheric pressure at sea level equals 1.01325 bar or 760 mmHg. This explains why weather forecasts in metric countries show normal pressure around 1013 millibar (1 millibar = 0.001 bar), while medical equipment uses 760 mmHg as the reference point.
Yes, the conversion formula works for vacuum (negative gauge pressure). For instance, -0.5 bar equals -375.031 mmHg. However, absolute pressure cannot be negative. When working with vacuum systems, ensure you distinguish between absolute pressure and gauge pressure (relative to atmospheric pressure).
The conversion factor 750.062 is accurate to six significant figures, derived from the precise definitions: 1 mmHg = 133.322387415 Pa and 1 bar = 100,000 Pa. For most practical applications, rounding to 750.06 or even 750 provides sufficient accuracy.
The standard definition of mmHg assumes 0°C (32°F) and standard gravity. Temperature affects mercury density, which slightly changes the pressure exerted by a mercury column. For high-precision work, corrections may apply, but for most practical conversions, the standard factor suffices.
References
- Bureau International des Poids et Mesures (BIPM). (2019). The International System of Units (SI), 9th edition. BIPM: Sèvres, France.
- National Institute of Standards and Technology (NIST). (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811.
- World Health Organization. (2020). Guidelines for Blood Pressure Measurement. WHO Technical Report Series.
- International Organization for Standardization. (2014). ISO 80000-4:2019 – Quantities and units – Part 4: Mechanics. ISO: Geneva, Switzerland.