Inches of Mercury to PSI Converter
Convert from Inches of Mercury (inHg) to Pounds per Square Inch (PSI)
Understanding Inches of Mercury and PSI
Inches of mercury (inHg) is a unit of pressure used in meteorology and aviation in the United States.
- Based on the height of a mercury column in a barometer
- Standard atmospheric pressure is approximately 29.92 inHg
- Common on weather reports and altimeters in the US
PSI (pound-force per square inch) is a unit of pressure in the imperial and US customary systems.
- Commonly used in the United States and the UK
- Standard atmospheric pressure is approximately 14.7 PSI
- Widely used for tire pressure, hydraulic systems, and many industrial applications
Conversion Formula
inHg to PSI:
PSI = inHg × 0.49115
To convert from inches of mercury to PSI, multiply the inHg value by approximately 0.49115.
PSI to inHg:
inHg = PSI × 2.03602
To convert from PSI to inches of mercury, multiply the PSI value by approximately 2.03602.
inHg to PSI Conversion Table
| Inches of Mercury (inHg) | Pounds per Square Inch (PSI) |
|---|---|
| 29.00 | 14.24 |
| 29.50 | 14.49 |
| 30.00 | 14.73 |
| 30.50 | 14.98 |
| 31.00 | 15.23 |
| 31.50 | 15.47 |
| 32.00 | 15.72 |
| 32.50 | 15.96 |
| 33.00 | 16.21 |
| 33.50 | 16.45 |
Historical Context and Applications
Historical Development
The mercury barometer was invented by Evangelista Torricelli in 1643, allowing precise measurement of atmospheric pressure as a column height. Inches of mercury became a standard unit in English-speaking countries. PSI evolved during the Industrial Revolution with the development of steam engines and other pressure-based technologies. Both units remain important in the American measurement system, though they are used in different contexts.
Common Applications
- inHg: Primarily used in weather forecasting, aviation (altimeters), and some specialized equipment in the United States.
- PSI: Used for measuring tire pressure, hydraulic and pneumatic systems, industrial equipment, plumbing, and various mechanical applications.
Practical Examples
- Standard atmospheric pressure: 29.92 inHg (14.7 PSI)
- Car tire pressure: 60-65 inHg (30-32 PSI)
- Hurricane conditions: <27.30 inHg (<13.4 PSI)
- Mountain altitude (10,000 ft): ~20.58 inHg (~10.1 PSI)
- Vacuum pump (high vacuum): 0.5 inHg (0.25 PSI)
- Enter your value in the inches of mercury (inHg) field
- The converter instantly displays the equivalent in PSI
- Use the swap button to convert from PSI to inches of mercury instead
- Results are displayed with 6 decimal places for precision
For quick reference without calculations, refer to the conversion table above for common values.