inHg to mmHg Converter

One inHg equals 25.40000362 mmHg (1 inHg = 25.40000362 mmHg). Multiply an inHg value by 25.40000362 to get the equivalent in mmHg. Enter your value in the calculator above. The formula and examples below show how to calculate it by hand.

Formula

mmHg = inHg × 25.40000362

Multiply the inHg value by 25.40000362 to get the equivalent value in mmHg.

Example Conversions

1 inHg (inHg)

25.40000362 mmHg (mmHg)

5 inHg (inHg)

127.0000181 mmHg (mmHg)

10 inHg (inHg)

254.0000362 mmHg (mmHg)

25 inHg (inHg)

635.0000905 mmHg (mmHg)

100 inHg (inHg)

2540.000362 mmHg (mmHg)

Conversion Table

Common conversion values from inHg to mmHg
inHg (inHg)mmHg (mmHg)
0.12.540000362
0.512.70000181
125.40000362
250.80000724
5127.0000181
10254.0000362
25635.0000905
501270.000181
1002540.000362
2506350.000905
50012700.00181
100025400.00362

How to Convert Manually

Use these steps to convert inHg values to mmHg without the calculator.

  1. Write down the value in inHg (inHg) that you want to convert.
  2. Multiply that value by 25.40000362.
  3. For example, 10 inHg × 25.40000362 = 254.0000362 mmHg.
  4. Label the result as mmHg (mmHg).

Relative Size Comparison

1 inHg
1 inHg
1 mmHg0.03937007313 inHg

This chart shows the visual difference in size between exactly one inHg and one mmHg.

About inHg and mmHg

The inch of mercury is about 3,386.39 pascals. US weather reports and aviation altimeter settings quote barometric pressure in inches of mercury. The millimeter of mercury is about 133.322 pascals, the height a pressure pushes a mercury column. Blood pressure worldwide is still reported in mmHg. One inHg equals 25.40000362 mmHg (1 inHg = 25.40000362 mmHg). inHg is used in US barometric weather reports and in aviation altimeter settings. mmHg is used in blood pressure readings.

Precision and Rounding:Several pressure factors are exact by definition (1 atm = 101,325 Pa; 1 bar = 100,000 Pa) while others, like psi and mmHg, are derived and carry long decimals. Tire and weather readings tolerate whole-number rounding; calibration, medicine, and process engineering need the full factor before rounding.

Use the pressure conversion guide to compare mmHg, mbar, inHg, kPa, Pa, and torr across medical, weather, aviation, vacuum, and engineering work.

Conversion factors per NIST Special Publication 811 and the BIPM SI Brochure (9th edition) (reference).

Worked Example

15inHg equals381.0000543mmHg.

15 inHg × 25.40000362 = 381.0000543 mmHg

FAQ

How do I convert inHg to mmHg?

Multiply the inHg value by 25.40000362 to get the equivalent value in mmHg.

What is the formula for inHg to mmHg?

The formula is mmHg = inHg × 25.40000362.

How many mmHg are in 1 inHg?

1 inHg equals 25.40000362 mmHg.

Can I convert mmHg back to inHg?

Yes. 1 mmHg equals 0.03937007313 inHg, and the related converter can reverse the calculation.

What are common names for inHg and mmHg?

inHg is shown as inHg and may also be searched as inches of mercury, in Hg. mmHg is shown as mmHg and may also be searched as millimeters of mercury, mm Hg.

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