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Convert Pounds per Square Inch to Inches of Mercury

Instantly convert Pounds per Square Inch (psi) to Inches of Mercury (inHg) with our free online calculator.

Reviewed by Christopher FloiedUpdated

Formula: psi to inHgmultiply by 2.03602

Reference Table

Pounds per Square Inch (psi)Inches of Mercury (inHg)
12.03602
510.1801
1020.3602
2550.9005
50101.801
100203.602

How to Convert Pounds per Square Inch to Inches of Mercury

Formula

To convert Pounds per Square Inch (psi) to Inches of Mercury (inHg): multiply by 2.03602

Step-by-Step

  1. Start with your value in Pounds per Square Inch (psi).
  2. Multiply by 2.03602 to perform the conversion.
  3. The result is your value expressed in Inches of Mercury (inHg).

Conversion Factor

1 psi = 2.03602 inHg

Reverse Factor

1 inHg = 0.491154 psi

Worked Example

Convert 25 Pounds per Square Inch to Inches of Mercury: 25 psi = 50.9005 inHg

About Pound per Square Inch (psi)

An imperial unit of pressure equal to one pound-force applied over one square inch (exactly 6,894.757 Pa per NIST SP 811). PSI is the dominant US pressure unit and remains the working unit in most US-built industrial, automotive, and consumer equipment: passenger-car tire inflation (32-35 psi cold), compressed air shop systems (typically 100-150 psi), hydraulic equipment (1,500-3,000 psi mobile, up to 10,000 psi on press brakes), ammunition chamber pressures (SAAMI specs in psi), municipal potable water supply (~40-80 psi at the meter), and natural gas distribution pressures. US engineering textbooks and the ASME B31 pipe codes, API piping specifications, and AWWA waterworks standards quote allowable pressures in psi. Engineers should distinguish gauge psi (psig — pressure above atmospheric) from absolute psi (psia — pressure above perfect vacuum); 0 psig = 14.696 psia at sea level. 1 psi = 6.895 kPa = 0.0689 bar = 51.715 mmHg.

About Inch of Mercury (inHg)

A pressure unit defined as the pressure exerted by a 1-inch column of mercury at the standard density of mercury (0 °C) and the standard acceleration of gravity (≈ 3,386.389 Pa per NIST SP 811). Inches of mercury are the primary unit in US aviation for altimeter settings (the QNH datum is reported in inHg in METAR weather observations — "Altimeter 30.12 inHg" means 30.12 inHg corrected to mean sea level), US barometric weather reporting on consumer indoor weather stations and TV weather graphics, HVAC and refrigeration duct/return static pressure (often quoted as fractions of an inHg, e.g., 0.25 inHg = ~62 Pa), and some legacy automotive vacuum gauges measuring intake-manifold vacuum below atmospheric (a healthy engine reads ~18-22 inHg of vacuum at idle). Standard sea-level atmospheric pressure is 29.92 inHg = 1013.25 hPa = 101.325 kPa.

Quick Facts

  • 1 Pound per Square Inch equals 2.03602 Inches of Mercury
  • 1 Inch of Mercury equals 0.491154 Pounds per Square Inch
  • Pound per Square Inch is a unit of pressure
  • Inch of Mercury is a unit of pressure
  • This conversion is commonly used in tire inflation, weather reporting, scuba diving, and engineering
  • The Pound per Square Inch belongs to the imperial system

Common Pound per Square Inch to Inch of Mercury Conversions

Pounds per Square Inch (psi)Inches of Mercury (inHg)
0.10.203602
0.51.01801
12.03602
24.07204
510.1801
1020.3602
14.69629.9213
1530.5403
2040.7204
2550.9005
50101.801
100203.602
150305.403
200407.204
5001018.01
10002036.02

Understanding Pounds per Square Inch

The Pound per Square Inch (symbol: psi) is a unit of pressure. An imperial unit of pressure equal to one pound-force applied over one square inch (exactly 6,894.757 Pa per NIST SP 811). PSI is the dominant US pressure unit and remains the working unit in most US-built industrial, automotive, and consumer equipment: passenger-car tire inflation (32-35 psi cold), compressed air shop systems (typically 100-150 psi), hydraulic equipment (1,500-3,000 psi mobile, up to 10,000 psi on press brakes), ammunition chamber pressures (SAAMI specs in psi), municipal potable water supply (~40-80 psi at the meter), and natural gas distribution pressures. US engineering textbooks and the ASME B31 pipe codes, API piping specifications, and AWWA waterworks standards quote allowable pressures in psi. Engineers should distinguish gauge psi (psig — pressure above atmospheric) from absolute psi (psia — pressure above perfect vacuum); 0 psig = 14.696 psia at sea level. 1 psi = 6.895 kPa = 0.0689 bar = 51.715 mmHg.

It belongs to the imperial measurement system.

Pounds per Square Inch are commonly used in tire inflation, weather reporting, scuba diving, and engineering.

Understanding Inches of Mercury

The Inch of Mercury (symbol: inHg) is a unit of pressure. A pressure unit defined as the pressure exerted by a 1-inch column of mercury at the standard density of mercury (0 °C) and the standard acceleration of gravity (≈ 3,386.389 Pa per NIST SP 811). Inches of mercury are the primary unit in US aviation for altimeter settings (the QNH datum is reported in inHg in METAR weather observations — "Altimeter 30.12 inHg" means 30.12 inHg corrected to mean sea level), US barometric weather reporting on consumer indoor weather stations and TV weather graphics, HVAC and refrigeration duct/return static pressure (often quoted as fractions of an inHg, e.g., 0.25 inHg = ~62 Pa), and some legacy automotive vacuum gauges measuring intake-manifold vacuum below atmospheric (a healthy engine reads ~18-22 inHg of vacuum at idle). Standard sea-level atmospheric pressure is 29.92 inHg = 1013.25 hPa = 101.325 kPa.

It belongs to the imperial measurement system.

Inches of Mercury are commonly used in tire inflation, weather reporting, scuba diving, and engineering.

Why Convert Pounds per Square Inch to Inches of Mercury?

Engineers, mechanics, and scientists frequently need to convert pressure between Pounds per Square Inch and Inches of Mercury when working with different measurement standards. Tire pressure, blood pressure readings, weather barometric measurements, and industrial process specifications may all use different pressure units depending on the region or discipline. Reliable conversion prevents equipment misuse and ensures safety.

Frequently Asked Questions

How do I convert Pounds per Square Inch to Inches of Mercury?

An imperial unit of pressure equal to one pound-force applied over one square inch (exactly 6,894. To convert Pounds per Square Inch to Inches of Mercury, multiply by 2.03602. For example, 25 psi equals 50.9005 inHg.

How many Inches of Mercury are in 1 Pound per Square Inch?

There are 2.03602 Inches of Mercury in 1 Pound per Square Inch.

How many Pounds per Square Inch are in 1 Inch of Mercury?

There are 0.491154 Pounds per Square Inch in 1 Inch of Mercury.

What is the formula for Pound per Square Inch to Inch of Mercury conversion?

The formula is: multiply by 2.03602. This means 1 psi = 2.03602 inHg.

Is a Pound per Square Inch bigger than a Inch of Mercury?

No. One Pound per Square Inch is smaller than one Inch of Mercury because 1 psi equals 2.03602 inHg, which is greater than 1.

When do you need to convert between Pounds per Square Inch and Inches of Mercury?

A pressure unit defined as the pressure exerted by a 1-inch column of mercury at the standard density of mercury (0 °C) and the standard acceleration of gravity (≈ 3,386. Pound per Square Inch and Inch of Mercury are both pressure units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.

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