Aviation Pressure Converter: inHg, hPa, psi, bar
Convert aviation altimeter settings, cabin pressures, and hydraulic system values instantly across inHg, mmHg, Pa, hPa, mbar, bar, atm, and psi.
Aviation Pressure Converter
How to Convert Aviation Pressure Units
Aircraft operations, meteorology, and maintenance engineering require precise pressure conversions across several international standards. This tool provides real-time translation between the primary pressure units used globally in aviation:
- Inches of Mercury (inHg): Standard unit for altimeter settings and barometric pressure in North America and Japan.
- HectoPascals (hPa) / Millibars (mbar): The international metric standard for altimeter settings (QNH/QFE) used by aviation authorities worldwide outside North America (1 hPa = 1 mbar).
- Pounds per Square Inch (psi): Standard unit for checking aircraft tire pressure, hydraulic system pressures, and pneumatic systems.
- Millimeters of Mercury (mmHg): Metric barometric unit used in legacy aviation systems and specific regional meteorological reports.
- Pascal (Pa): The foundational SI unit of pressure (1 Newton per square meter).
- Bar (bar) & Atmosphere (atm): High-pressure reference units used primarily in component testing, oxygen system charging, and structural inflation.
Aviation Pressure Applications
Accurate pressure adjustment is safety-critical for maintaining aircraft separation, verifying instrument readings, and servicing aircraft systems.
| Application | Primary Units Used | Operational Context |
| Altimeter Settings (QNH / QFE) | inHg / hPa / mbar | Used to calibrate altimeters. Standard sea-level pressure is 29.92 inHg or 1013.25 hPa. |
| Aircraft Tire Maintenance | psi / bar | Checked cold during pre-flight or scheduled maintenance to prevent blowouts during landing. |
| Hydraulic Systems | psi / bar | Commercial transport aircraft systems typically operate at high pressures (e.g., 3,000 psi to 5,000 psi). |
| Cabin Pressurization | psi / differential psi (Delta P) | Measures the structural pressure difference between the cabin interior and the thin air outside at cruise altitudes. |
Complete Pressure Conversion Formulas
Inches of Mercury (inHg) Conversions
- inHg to mmHg: mmHg = inHg × 25.4
- inHg to Pa: Pa = inHg × 3386.39
- inHg to hPa/mbar: hPa = inHg × 33.8639
- inHg to bar: bar = inHg × 0.0338639
- inHg to atm: atm = inHg × 0.0334211
- inHg to psi: psi = inHg × 0.491154
Millimeters of Mercury (mmHg) Conversions
- mmHg to inHg: inHg = mmHg / 25.4
- mmHg to Pa: Pa = mmHg × 133.322
- mmHg to hPa/mbar: hPa = mmHg × 1.33322
- mmHg to bar: bar = mmHg × 0.00133322
- mmHg to atm: atm = mmHg × 0.00131579
- mmHg to psi: psi = mmHg × 0.0193368
Pascal (Pa) Conversions
- Pa to inHg: inHg = Pa × 0.000295333
- Pa to mmHg: mmHg = Pa × 0.00750062
- Pa to hPa/mbar: hPa = Pa × 0.01
- Pa to bar: bar = Pa × 0.00001
- Pa to atm: atm = Pa × 0.00000986923
- Pa to psi: psi = Pa × 0.000145037
HectoPascal (hPa) / Millibar (mbar) Conversions
- hPa to inHg: inHg = hPa × 0.0295299
- hPa to mmHg: mmHg = hPa × 0.750062
- hPa to Pa: Pa = hPa × 100
- hPa to bar: bar = hPa × 0.001
- hPa to atm: atm = hPa × 0.000986923
- hPa to psi: psi = hPa × 0.0145037
Bar (bar) Conversions
- bar to inHg: inHg = bar × 29.5300
- bar to mmHg: mmHg = bar × 750.062
- bar to Pa: Pa = bar × 100,000
- bar to hPa/mbar: hPa = bar × 1,000
- bar to atm: atm = bar × 0.986923
- bar to psi: psi = bar × 14.5038
Atmosphere (atm) Conversions
- atm to inHg: inHg = atm × 29.9212
- atm to mmHg: mmHg = atm × 760
- atm to Pa: Pa = atm × 101,325
- atm to hPa/mbar: hPa = atm × 1013.25
- atm to bar: bar = atm × 1.01325
- atm to psi: psi = atm × 14.6959
Pounds per Square Inch (psi) Conversions
- psi to inHg: inHg = psi × 2.03602
- psi to mmHg: mmHg = psi × 51.7149
- psi to Pa: Pa = psi × 6894.76
- psi to hPa/mbar: hPa = psi × 68.9476
- psi to bar: bar = psi × 0.0689476
- psi to atm: atm = psi × 0.068046
Pressure Units Quick Reference Matrix
| From Unit | To inHg | To mmHg | To Pa | To hPa / mbar | To bar | To atm | To psi |
| 1 inHg | 1 | 25.4 | 3,386.39 | 33.8639 | 0.0338639 | 0.0334211 | 0.491154 |
| 1 mmHg | 0.0393701 | 1 | 133.322 | 1.33322 | 0.00133322 | 0.00131579 | 0.0193368 |
| 1 Pa | 0.000295333 | 0.00750062 | 1 | 0.01 | 0.00001 | 0.000009869 | 0.000145037 |
| 1 hPa / mbar | 0.0295299 | 0.750062 | 100 | 1 | 0.001 | 0.000986923 | 0.0145037 |
| 1 bar | 29.5300 | 750.062 | 100,000 | 1,000 | 1 | 0.986923 | 14.5038 |
| 1 atm | 29.9212 | 760 | 101,325 | 1,013.25 | 1.01325 | 1 | 14.6959 |
| 1 psi | 2.03602 | 51.7149 | 6,894.76 | 68.9476 | 0.0689476 | 0.068046 | 1 |