mmHg to PSI Converter

mmHg to PSI

Convert mmhg (mmHg) to psi (psi). Both measure force per area, and the conversion comes up in weather, automotive, diving work.

The Formula

`` psi = mmhg × 0.0193367774595 mmhg = psi × 51.7149252039 `

One mmhg is 0.019337 psi, and one psi is 51.7149 mmhg.

Conversion Table

mmHg	PSI
1 mmHg	0.019337 psi
2 mmHg	0.038674 psi
5 mmHg	0.096684 psi
10 mmHg	0.193368 psi
25 mmHg	0.483419 psi
50 mmHg	0.966839 psi
100 mmHg	1.9337 psi
500 mmHg	9.6684 psi
1,000 mmHg	19.3368 psi

The Other Direction

PSI	mmHg
1 psi	51.7149 mmHg
2 psi	103.4299 mmHg
5 psi	258.5746 mmHg
10 psi	517.1493 mmHg
25 psi	1,292.87 mmHg
50 psi	2,585.75 mmHg
100 psi	5,171.49 mmHg
500 psi	25,857.46 mmHg
1,000 psi	51,714.93 mmHg

What Each Unit Is

mmHg (mmHg) — the pressure of a one-millimetre column of mercury, or 133.322 pascals. From the mercury barometer; medicine kept it after physics moved to pascals.

PSI (psi) — pounds-force per square inch, equal to 6,894.76 pascals. The imperial pressure unit, still standard for US tyres, plumbing and compressed air.

A Sense of Scale

• Normal blood pressure is 120/80 mmHg
• Atmospheric pressure is 760 mmHg
• Car tyres run at 32–35 psi
• Household water is 40–60 psi

Precision

The factor 0.0193367774595 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.

In Code

`javascript const mmHgToPsi = (value) => value * 0.0193367774595; ``

Where This Conversion Comes Up

• Weather
• Automotive
• Diving
• Aviation
• HVAC

How Many Decimals Do You Need?

Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 mmHg with the factor truncated at each decimal place:

Decimals kept	Factor	137 mmHg becomes	Error
0	0	0	100.0000%
1	0	0	100.0000%
2	0.02	2.74	3.4299%
3	0.019	2.603	1.7416%
4	0.0193	2.6441	0.1902%

A rule that holds for any conversion: round once, at the end. Rounding the factor and then multiplying compounds the error through every subsequent calculation, while carrying full precision and rounding the final answer does not.

The right number of significant figures is set by your input, not by the converter. If you measured mmhg to three significant figures, the answer in psi is only good to three — writing more digits claims precision the measurement never had.

Other Conversions From mmHg

The same value in every other unit this converter supports for pressure:

From	To	Unit
1 mmHg	133.322 Pa	Pascals
1 mmHg	0.133322 kPa	Kilopascals
1 mmHg	0.00133322 bar	Bar
1 mmHg	0.00131579 atm	Atmospheres

Chaining conversions works — mmhg to metres to feet gives the same answer as mmhg to feet — but each step rounds, so a chain of three conversions carries three roundings. Convert directly where a direct factor exists.