Convert Millimetre of mercury to Standard atmosphere
1 millimetre of mercury = 0.00131579 standard atmosphere (atm). For example, 10 millimetre of mercury = 0.0131579 standard atmosphere and 100 millimetre of mercury = 0.131579 standard atmosphere. Type any value below to convert millimetre of mercury to standard atmosphere both ways โ it runs entirely in your browser.
Quick answer: Millimetre of mercury to Standard atmosphere
1 Millimetre of mercury = 0.00131579 Standard atmosphere (mmHg โ atm). To convert millimetre of mercury to standard atmosphere, multiply by 0.00131579. To convert standard atmosphere to millimetre of mercury, multiply by 759.9999. The converter at the top does this instantly and both ways; the sections below give the formula, worked examples, a full conversion chart and answers to the most common millimetre of mercury-to-standard atmosphere questions.
How to convert Millimetre of mercury to Standard atmosphere
To convert millimetre of mercury to standard atmosphere, multiply the number of millimetre of mercury by the conversion factor 0.00131579, because 1 mmHg = 0.00131579 atm. The conversion is linear, so the same factor works for any value โ whole numbers, decimals or fractions. For the reverse direction, 1 atm = 759.9999 mmHg, so you divide by 0.00131579 (or multiply by 759.9999) to turn standard atmosphere back into millimetre of mercury.
atm = mmHg ร 0.00131579 ยท
mmHg = atm ร 759.9999
- Write down the value you want to convert, in millimetre of mercury.
- Multiply it by 0.00131579.
- The result is the same area/length/quantity expressed in standard atmosphere.
Millimetre of mercury to Standard atmosphere โ worked examples
Each row shows the exact arithmetic so you can follow the conversion step by step. For example, 5 millimetre of mercury is 0.006578948 standard atmosphere because 5 mmHg ร 0.00131579 = 0.006578948 atm.
| Millimetre of mercury | Calculation | Standard atmosphere |
|---|---|---|
| 1 mmHg | 1 mmHg ร 0.00131579 = 0.00131579 atm | 0.00131579 atm |
| 2 mmHg | 2 mmHg ร 0.00131579 = 0.002631579 atm | 0.002631579 atm |
| 3 mmHg | 3 mmHg ร 0.00131579 = 0.003947369 atm | 0.003947369 atm |
| 5 mmHg | 5 mmHg ร 0.00131579 = 0.006578948 atm | 0.006578948 atm |
| 7 mmHg | 7 mmHg ร 0.00131579 = 0.009210528 atm | 0.009210528 atm |
| 10 mmHg | 10 mmHg ร 0.00131579 = 0.0131579 atm | 0.0131579 atm |
| 12 mmHg | 12 mmHg ร 0.00131579 = 0.01578948 atm | 0.01578948 atm |
| 15 mmHg | 15 mmHg ร 0.00131579 = 0.01973684 atm | 0.01973684 atm |
| 20 mmHg | 20 mmHg ร 0.00131579 = 0.02631579 atm | 0.02631579 atm |
| 25 mmHg | 25 mmHg ร 0.00131579 = 0.03289474 atm | 0.03289474 atm |
| 50 mmHg | 50 mmHg ร 0.00131579 = 0.06578948 atm | 0.06578948 atm |
| 100 mmHg | 100 mmHg ร 0.00131579 = 0.131579 atm | 0.131579 atm |
Common Millimetre of mercury to Standard atmosphere conversions
These are the millimetre of mercury-to-standard atmosphere values people look up most often. Every figure is computed from the exact factor, so you can rely on them for quick reference:
- 1 millimetre of mercury = 0.00131579 standard atmosphere
- 2 millimetre of mercury = 0.002631579 standard atmosphere
- 2.5 millimetre of mercury = 0.003289474 standard atmosphere
- 3 millimetre of mercury = 0.003947369 standard atmosphere
- 4 millimetre of mercury = 0.005263159 standard atmosphere
- 5 millimetre of mercury = 0.006578948 standard atmosphere
- 6 millimetre of mercury = 0.007894738 standard atmosphere
- 7 millimetre of mercury = 0.009210528 standard atmosphere
- 8 millimetre of mercury = 0.01052632 standard atmosphere
- 9 millimetre of mercury = 0.01184211 standard atmosphere
- 10 millimetre of mercury = 0.0131579 standard atmosphere
- 12 millimetre of mercury = 0.01578948 standard atmosphere
- 15 millimetre of mercury = 0.01973684 standard atmosphere
- 20 millimetre of mercury = 0.02631579 standard atmosphere
- 25 millimetre of mercury = 0.03289474 standard atmosphere
- 30 millimetre of mercury = 0.03947369 standard atmosphere
- 50 millimetre of mercury = 0.06578948 standard atmosphere
- 75 millimetre of mercury = 0.09868422 standard atmosphere
- 100 millimetre of mercury = 0.131579 standard atmosphere
- 200 millimetre of mercury = 0.2631579 standard atmosphere
- 500 millimetre of mercury = 0.6578948 standard atmosphere
- 1000 millimetre of mercury = 1.31579 standard atmosphere
Millimetre of mercury to Standard atmosphere conversion chart (both directions)
The chart below converts millimetre of mercury to standard atmosphere and standard atmosphere to millimetre of mercury side by side, so it works whichever way you need. 1 millimetre of mercury = 0.00131579 standard atmosphere, and 1 standard atmosphere = 759.9999 millimetre of mercury.
| Millimetre of mercury โ Standard atmosphere | Standard atmosphere โ Millimetre of mercury |
|---|---|
| 0.25 mmHg = 0.0003289474 atm | 0.25 atm = 190 mmHg |
| 0.5 mmHg = 0.0006578948 atm | 0.5 atm = 379.9999 mmHg |
| 1 mmHg = 0.00131579 atm | 1 atm = 759.9999 mmHg |
| 2 mmHg = 0.002631579 atm | 2 atm = 1,520 mmHg |
| 3 mmHg = 0.003947369 atm | 3 atm = 2,280 mmHg |
| 4 mmHg = 0.005263159 atm | 4 atm = 3,040 mmHg |
| 5 mmHg = 0.006578948 atm | 5 atm = 3,799.999 mmHg |
| 6 mmHg = 0.007894738 atm | 6 atm = 4,559.999 mmHg |
| 7 mmHg = 0.009210528 atm | 7 atm = 5,319.999 mmHg |
| 8 mmHg = 0.01052632 atm | 8 atm = 6,079.999 mmHg |
| 9 mmHg = 0.01184211 atm | 9 atm = 6,839.999 mmHg |
| 10 mmHg = 0.0131579 atm | 10 atm = 7,599.999 mmHg |
| 12 mmHg = 0.01578948 atm | 12 atm = 9,119.999 mmHg |
| 15 mmHg = 0.01973684 atm | 15 atm = 11,400 mmHg |
| 20 mmHg = 0.02631579 atm | 20 atm = 15,200 mmHg |
| 25 mmHg = 0.03289474 atm | 25 atm = 19,000 mmHg |
| 30 mmHg = 0.03947369 atm | 30 atm = 22,800 mmHg |
| 40 mmHg = 0.05263159 atm | 40 atm = 30,400 mmHg |
| 50 mmHg = 0.06578948 atm | 50 atm = 37,999.99 mmHg |
| 75 mmHg = 0.09868422 atm | 75 atm = 56,999.99 mmHg |
| 100 mmHg = 0.131579 atm | 100 atm = 75,999.99 mmHg |
| 150 mmHg = 0.1973684 atm | 150 atm = 114,000 mmHg |
| 200 mmHg = 0.2631579 atm | 200 atm = 152,000 mmHg |
| 250 mmHg = 0.3289474 atm | 250 atm = 190,000 mmHg |
| 500 mmHg = 0.6578948 atm | 500 atm = 379,999.9 mmHg |
| 1000 mmHg = 1.31579 atm | 1000 atm = 759,999.9 mmHg |
Millimetre of mercury vs Standard atmosphere: which is bigger?
A standard atmosphere is the larger unit: one standard atmosphere equals 759.9999 millimetre of mercurys. Put another way, you need 759.9999 millimetre of mercurys to make a single standard atmosphere.
What is a Millimetre of mercury? History, origin and usage
Measuring pressure by the height of a mercury column dates to Torricelli in 1643 and became the standard laboratory method for three centuries. Mercury was chosen because it is dense enough to keep the tube a manageable length โ a water barometer measuring the same pressure would need to be over ten metres tall. The modern unit no longer depends on real mercury: it is fixed at exactly 133.322387415 pascals, the value a millimetre of mercury would give at a conventional density of 13,595.1 kg per cubic metre under standard gravity.
Millimetres of mercury are the universal unit of blood pressure โ a reading of "120 over 80" means 120 mmHg when the heart contracts and 80 mmHg between beats. They are also used for eye pressure, cerebrospinal fluid pressure and some vacuum work.
Mercury sphygmomanometers are being retired worldwide because of the toxicity of mercury, yet the unit has outlived the instrument: digital monitors with no mercury in them still report in mmHg, because a century of medical guidance is written in it.
What is a Standard atmosphere? History, origin and usage
The standard atmosphere was fixed by the 10th General Conference on Weights and Measures in 1954 at exactly 101,325 pascals. Before that, "one atmosphere" meant whatever a 760 mm mercury column happened to weigh, which depended on local gravity and on the temperature of the mercury โ so the same experiment gave slightly different answers in different laboratories. Fixing it as a defined number ended that.
Atmospheres are used in chemistry, physics, diving and any field that talks about pressure as a multiple of ordinary air pressure โ reaction conditions, gas laws, hyperbaric medicine and pressure-vessel ratings.
It is a defined constant, not a measurement, so it never changes with the weather or with where you are standing. Real sea-level pressure wanders a few per cent either side of it every week. The deepest point of the ocean sits at roughly 1,100 atmospheres.
Convert 1 Millimetre of mercury to other units
It can help to see a millimetre of mercury next to the other units it is commonly compared with. One millimetre of mercury (mmHg) is equal to:
| 1 Millimetre of mercury equals | Unit |
|---|---|
| 133.3224 Pa | Pascal |
| 1.333224 hPa | Hectopascal |
| 0.1333224 kPa | Kilopascal |
| 0.0001333224 MPa | Megapascal |
| 1.333224 mbar | Millibar |
| 0.001333224 bar | Bar |
| 0.00131579 atm | Standard atmosphere |
| 1 Torr | Torr |
| 0.03937008 inHg | Inch of mercury |
| 13.5951 mmHโO | Millimetre of water |
| 0.5352402 inHโO | Inch of water |
| 0.01933678 psi | Pound per square inch |
| 0.00135951 kgf/cmยฒ | Kilogram-force per square centimetre |
Convert 1 Standard atmosphere to other units
One standard atmosphere (atm) is equal to:
| 1 Standard atmosphere equals | Unit |
|---|---|
| 101,325 Pa | Pascal |
| 1,013.25 hPa | Hectopascal |
| 101.325 kPa | Kilopascal |
| 0.101325 MPa | Megapascal |
| 1,013.25 mbar | Millibar |
| 1.01325 bar | Bar |
| 760 Torr | Torr |
| 759.9999 mmHg | Millimetre of mercury |
| 29.92126 inHg | Inch of mercury |
| 10,332.27 mmHโO | Millimetre of water |
| 406.7825 inHโO | Inch of water |
| 14.69595 psi | Pound per square inch |
| 1.033227 kgf/cmยฒ | Kilogram-force per square centimetre |
Tips for converting Millimetre of mercury to Standard atmosphere
- To go from millimetre of mercury to standard atmosphere, multiply by 0.00131579; to go back, divide by 0.00131579 (or multiply by 759.9999).
- For a quick mental estimate, remember that 1 millimetre of mercury โ 0.00131579 standard atmosphere, so 10 millimetre of mercury โ 0.0131579 standard atmosphere.
- The converter above keeps full precision; the tables round for readability, so use the tool for exact figures.
- Both fields update live as you type โ change either side to convert in that direction.
How to use this Millimetre of mercury to Standard atmosphere converter
Type a number into the Millimetre of mercury field and the equivalent in Standard atmosphere appears instantly โ there is no โconvertโ button to press and nothing is sent to a server, so it works offline once the page has loaded and is safe for any data. You can also type into the Standard atmosphere field to convert the other way (standard atmosphere to millimetre of mercury). Use the swap control to flip the two units, and copy the result with a single click. Because the calculation runs in your browser with full floating-point precision, the converter is more exact than the rounded figures shown in the reference chart above โ use the chart for quick look-ups and the tool for precise work.
Accuracy and method
Every figure on this page โ the formula, the worked examples, the conversion chart and the โconvert to other unitsโ tables โ is computed from a single verified conversion factor (1 mmHg = 0.00131579 atm), never copied from a hand-typed lookup table that could drift. That factor is derived from each unitโs definition in terms of a common base unit, and an automated check re-verifies all of the siteโs factors on every update, so the numbers here stay correct over time. This matters for millimetre of mercury-to-standard atmosphere conversions because a small rounding error in a published table compounds quickly at larger quantities; computing from the exact factor avoids that.
Sources
- BIPM โ The International System of Units (SI Brochure) โ the defining document for the SI, published by the International Bureau of Weights and Measures. It fixes the base unit that this conversion resolves to, which is why the factor here can be exact rather than approximate.
- NIST โ Definitions of the SI base units โ the US National Institute of Standards and Technology reference for the SI base units, used here as an independent cross-check on the base-unit definition.
Pressure factors here come from fixed definitions, anchored to the pascal: a bar is exactly 100,000 Pa, one atmosphere is exactly 101,325 Pa, a torr is exactly a 760th of an atmosphere, and psi is built from the exact pound and the exact inch. Two of them โ psi and the torr โ work out to decimals that repeat forever, so where a number is shown rounded it is marked, not quietly trimmed.
Frequently asked questions
- How many standard atmosphere are in 1 millimetre of mercury?
- 1 millimetre of mercury = 0.00131579 standard atmosphere (atm). To convert any number of millimetre of mercury to standard atmosphere, multiply by 0.00131579.
- How do I convert millimetre of mercury to standard atmosphere?
- Multiply the number of millimetre of mercury by 0.00131579. For example, 10 millimetre of mercury = 10 ร 0.00131579 = 0.0131579 standard atmosphere, and 25 millimetre of mercury = 0.03289474 standard atmosphere.
- How many millimetre of mercury are in 1 standard atmosphere?
- 1 standard atmosphere = 759.9999 millimetre of mercury. So to convert standard atmosphere back to millimetre of mercury, multiply by 759.9999.
- What is the formula to convert millimetre of mercury to standard atmosphere?
- standard atmosphere = millimetre of mercury ร 0.00131579. The reverse formula is millimetre of mercury = standard atmosphere ร 759.9999.
- How much is 100 millimetre of mercury in standard atmosphere?
- 100 millimetre of mercury = 0.131579 standard atmosphere. (And 1000 millimetre of mercury = 1.31579 standard atmosphere.)
- Which is bigger, a millimetre of mercury or a standard atmosphere?
- A standard atmosphere is larger: 1 standard atmosphere = 759.9999 millimetre of mercury.
- Is this millimetre of mercury to standard atmosphere converter accurate?
- Yes โ every value is computed from the exact 0.00131579 atm per mmHg factor (not rounded look-up tables), and the factors are re-verified automatically on every update.
- Can I convert standard atmosphere to millimetre of mercury too?
- Yes. The converter works both ways โ enter a value in either field. 1 standard atmosphere = 759.9999 millimetre of mercury.