1 inHg is equal to approximately 25.4 mmHg.
The conversion from inches of mercury (inHg) to millimeters of mercury (mmHg) involves using the fixed relationship between these two pressure units. Since 1 inHg equals exactly 25.4 mmHg, multiplying the value in inHg by 25.4 gives the equivalent pressure in mmHg.
Conversion Tool
Result in mmhg:
Conversion Formula
The formula to convert from inches of mercury (inHg) to millimeters of mercury (mmHg) is straightforward:
mmHg = inHg × 25.4
This works because one inch equals exactly 25.4 millimeters by international agreement. Since both units measure pressure based on the height of a mercury column, the conversion between the two is direct and linear.
For example, converting 1 inHg:
- Start with 1 inHg.
- Multiply 1 by 25.4.
- Result: 1 × 25.4 = 25.4 mmHg.
This shows that 1 inHg equals 25.4 mmHg exactly, without approximation.
Conversion Example
- 2.5 inHg to mmHg:
- Multiply 2.5 by 25.4.
- 2.5 × 25.4 = 63.5 mmHg.
- Therefore, 2.5 inHg equals 63.5 mmHg.
- 0.75 inHg to mmHg:
- Multiply 0.75 by 25.4.
- 0.75 × 25.4 = 19.05 mmHg.
- So, 0.75 inHg equals 19.05 mmHg.
- 10 inHg to mmHg:
- Multiply 10 by 25.4.
- 10 × 25.4 = 254 mmHg.
- Thus, 10 inHg equals 254 mmHg.
Conversion Chart
| inHg | mmHg |
|---|---|
| -24.0 | -609.6 |
| -20.0 | -508.0 |
| -15.0 | -381.0 |
| -10.0 | -254.0 |
| -5.0 | -127.0 |
| 0.0 | 0.0 |
| 5.0 | 127.0 |
| 10.0 | 254.0 |
| 15.0 | 381.0 |
| 20.0 | 508.0 |
| 26.0 | 660.4 |
This chart shows the conversion of inHg values from -24.0 to 26.0 into mmHg by multiplying each value by 25.4. Use the chart to quickly find equivalent mmHg values without calculation, useful for negative or positive pressures.
Related Conversion Questions
- How many mmHg are in 1 inHg exactly?
- What’s the formula to convert 1 inHg to mmHg?
- Is 1 inHg greater or less than 25 mmHg?
- Can 1 inHg be used interchangeably with 25.4 mmHg in measurements?
- Why does 1 inHg equal 25.4 mmHg in pressure units?
- How to convert 1.5 inHg to mmHg manually?
- Does 1 inHg equal 25.4 mmHg in all conditions?
Conversion Definitions
inhg: Inches of mercury (inHg) is a unit of pressure based on the height of a mercury column measured in inches. It is used in barometers and manometers to express atmospheric pressure and other pressure readings, especially in the United States and aviation.
mmhg: Millimeters of mercury (mmHg) is a pressure unit that measures the height of a mercury column in millimeters. It is commonly used in medicine, meteorology, and physics to represent blood pressure and atmospheric pressure.
Conversion FAQs
Why is the conversion factor between inHg and mmHg exactly 25.4?
The conversion factor comes from the definition of an inch as exactly 25.4 millimeters internationally. Since both inHg and mmHg measure pressure by mercury column height, converting inches to millimeters gives the precise factor for pressure conversion.
Can temperature or gravity affect the inHg to mmHg conversion?
In theory, temperature and gravity can influence mercury density and pressure readings, but the inHg to mmHg conversion uses standard conditions where these effects are negligible. For most practical purposes, the conversion factor 25.4 holds constant.
Is the conversion between inHg and mmHg linear for all pressure ranges?
Yes, since both units measure column heights, the relation is linear. Doubling an inHg value will double the mmHg value. However, extreme pressures or conditions might require more precise instruments, but the formula remains valid.
Why do aviation and meteorology often use inHg instead of mmHg?
In the US, aviation and weather reports use inHg due to historical measurement systems and convenience. The inch unit aligns with other imperial measurements still common in the region, although mmHg is preferred in scientific and medical fields.
Can I convert pressure values in inHg to other units like pascals?
Yes, by first converting inHg to mmHg, then using further conversion to pascals or atmospheres. One mmHg equals approximately 133.322 pascals, so multiple conversions are possible depending on needed units.