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Bar to mmHg Converter
↔ Convert mmHg to bar instead

Common Conversions

bar mmHg
0.01 7.501
0.05 37.503
0.1 75.006
0.25 187.516
0.5 375.031
1 750.062
1.01325 760
1.5 1125.093
2 1500.124
5 3750.31
10 7500.62

Why this conversion matters in chemistry

Antoine-equation tables and other classic vapor-pressure references use mmHg. Modern industrial vapor-pressure curves and IUPAC-standard thermodynamic data use bar. The conversion is a multiply by 750.062 — a factor that looks ugly but drops directly out of 1 atm = 760 mmHg combined with 1 atm = 1.01325 bar. Water's vapor pressure at 100°C is 1.01325 bar, which reads as 760 mmHg; at 25°C, 0.0317 bar reads as 23.8 mmHg. Reading across bar-based and mmHg-based data is the main use case, and the conversion is exact by construction.

Formula

mmHg = bar × 750.062

Worked Examples

1 bar = 750.062 mmHg

IUPAC standard pressure. Just below 1 atm, which is where the 10 mmHg gap between 1 bar and 1 atm originates.

1.01325 bar = 760 mmHg

Sea-level atmospheric pressure expressed in both units. The anchor that ties the two scales together.

0.5 bar = 375.031 mmHg

A moderate reduced pressure, typical for rotovap distillation of mid-volatility solvents.

2 bar = 1500.12 mmHg

Roughly the elevated pressure inside an autoclave at 121°C during steam sterilization.

Frequently Asked Questions

How do I convert bar to mmHg?
Multiply by 750.062. So 1 bar becomes 750 mmHg, 2 bar becomes 1500 mmHg. Close enough to a factor of 750 that you can ballpark in your head when you're checking whether an old vapor-pressure value and a new measurement agree.
How many mmHg in 1 bar?
750.062. Slightly less than 1 atm (760 mmHg), because 1 bar is exactly 100,000 Pa while 1 atm is 101,325 Pa. The 10 mmHg gap between the two is a 1.3% difference — usually lost in the rounding of routine measurements.
Why did chemistry move to bar?
Since 1982, IUPAC has recommended 1 bar (100 kPa exactly) as the standard pressure for thermodynamic data, in place of the older 1 atm. The bar plays more cleanly with SI — 1 bar is exactly 10⁵ Pa, no awkward 101,325 factor — so calculations using the gas constant R in SI units stay dimensionally neat.
What's the difference between bar and atm in mmHg?
1 bar is 750.062 mmHg; 1 atm is 760 mmHg. The 10 mmHg gap is 1.3%, which usually doesn't matter for practical calculations but does matter when reading across thermodynamic tables from different eras. Pre-1982 tables use 1 atm as the standard state; post-1982 tables use 1 bar.