Convert pressure units — Pascal, bar, PSI, atm, Torr, mmHg.
| Unit | Name | Value |
|---|---|---|
| Pa | Pascal | 3386.39 |
| kPa | Kilopascal | 3.38639 |
| bar | Bar | 0.0338639 |
| atm | Atmosphere | 0.033421071 |
| psi | PSI | 0.49115415 |
| Torr | Torr / mmHg | 25.400084 |
Formula: Torr = Inch Hg × 25.4
Multiply any inch hg value by 25.4 to get torr.
Reverse: Inch Hg = Torr × 0.03937
Common inch hg values — factor: 1 inHg = 25.4 Torr
| Inch Hg (inHg) | Torr (Torr) | Context |
|---|---|---|
| 0.01 inHg | 0.254 Torr | Near vacuum |
| 0.1 inHg | 2.54 Torr | Very low |
| 1 inHg | 25.4 Torr | Low pressure |
| 10 inHg | 254 Torr | ~10 inHg |
| 20 inHg | 508 Torr | ~20 inHg |
| 25 inHg | 635 Torr | Low weather |
| 28 inHg | 711.2 Torr | Hurricane center |
| 29 inHg | 736.6 Torr | Storm low |
| 29.92 inHg | 760 Torr | 1 standard atm |
| 30 inHg | 762 Torr | Slightly high |
| 31 inHg | 787.4 Torr | High pressure |
| 35 inHg | 889 Torr | Very high |
| 50 inHg | 1,270 Torr | ~1.67 atm |
| 100 inHg | 2,540 Torr | ~3.34 atm |
| 1,000 inHg | 2.54e+04 Torr | ~33.4 atm |
1 inHg = 25.4 Torr. Memorize for instant estimates.
Use 25.4 as a quick mental multiplier.
Multiply result by 0.03937 to recover the original inHg value.
Sets altimeter QNH and reads weather ATIS in inHg — standard US aviation.
Reports barometric pressure in inHg for US television and radio weather.
Measures duct static pressure in inches of water column or inHg in US systems.
Checks HVAC system static pressure and duct leakage in inHg.
Logs surface pressure in inHg for propagation prediction and wx stations.
References inHg barometric pressure when using US-spec nautical instruments.
Inches of mercury (inHg) is the pressure unit used in US aviation and weather reporting, defined as the pressure exerted by a 1-inch column of mercury (3,386.39 Pa). It has been standard in US aviation since the early 20th century.
US aviation altimeters are set in inHg (standard: 29.92 inHg). US weather broadcasts report barometric pressure in inHg. HVAC engineers in the US use inHg for duct static pressure measurements.
Interesting fact: Pilots set their altimeter to the local QNH (pressure at sea level) in inHg to ensure their altitude reading is accurate — a difference of 0.1 inHg causes an altimeter error of about 100 feet.
The torr was named after Evangelista Torricelli, who invented the mercury barometer in 1644. One torr is defined as 1/760 of standard atmospheric pressure (133.322 Pa), and is equal to 1 mmHg at 0°C.
Torr is the standard pressure unit in vacuum science and semiconductor manufacturing. High vacuum systems operate at 10⁻³ to 10⁻⁷ torr. Ultra-high vacuum (used in particle accelerators) reaches below 10⁻¹⁰ torr.
Interesting fact: Torricelli's original barometer experiment used a 1-meter tube of mercury that settled at 760 mm above the reservoir — directly defining the unit that would later bear his name.
Converting inch hg to torr is a common task in engineering, medicine, meteorology, and science. Different industries and countries use different pressure units — PSI in the US, bar in Europe, mmHg in medicine, and pascals in physics — making accurate conversion essential for cross-disciplinary work.
Quick reference: 5 inHg = 127 Torr and 10 inHg = 254 Torr. For the reverse: 1 Torr = 0.03937 inHg. The exact factor is 1 inHg = 25.4 Torr.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.