Select a category and enter your values below
To convert a pressure from millimeters of mercury (mmHg) to pascals (Pa), multiply by 133.322.
The factor is the pressure exerted by a 1 mm column of mercury at 0 °C under standard gravity — mercury's density (13,595.1 kg/m³) times 9.80665 m/s² times 0.001 m. The conventional millimeter of mercury is defined as exactly 133.322387415 Pa; the rounded 133.322 used here differs by three parts per million, far below what any instrument resolves.
The anchor that fixes the scale:
A blood-pressure reading of 120 mmHg systolic needs to be expressed in SI for a physiology model:
That is 16.0 kPa — the figure a European clinical paper would print for the same patient. A normal systolic pressure is, in SI terms, about a sixth of an atmosphere above ambient.
| mmHg | Pa |
|---|---|
| 1 | 133.3 |
| 10 | 1,333 |
| 40 | 5,333 |
| 80 | 10,666 |
| 120 | 15,999 |
| 760 | 101,325 |
Nearly every other pressure conversion modernizes an old unit for convenience; this one is usually compulsory. The pascal is the only pressure unit that cancels correctly inside SI formulas, so any mmHg value entering a calculation — flow through an airway resistance, gas solubility from a partial pressure, force on a diaphragm — must be converted first. Medicine supplies most of the input: blood pressure, intraocular pressure, intracranial pressure, and blood-gas partial pressures are all recorded in mmHg in North America and much of the world, while the journals, ISO standards and sensor datasheets those readings feed into are written in Pa or kPa. Vacuum technology supplies the rest, since rough-vacuum work quotes torr, practically identical to mmHg, and pump curves increasingly arrive in pascals.
Two habits keep the results trustworthy. First, convert once, at the boundary, rather than hopping between units mid-calculation, so the truncated factor cannot accumulate. Second, watch the reference frame: clinical pressures are gauge values relative to atmosphere, so 120 mmHg is 16 kPa above ambient, or about 117 kPa absolute — a distinction that matters the moment a calculation involves gas laws, where only absolute pressure is physically meaningful.
How many millimeters of mercury are in one pascal? One pascal (Pa) contains 0.007500637554192106329 millimeters of mercury (mmHg) — the inverse of the factor above. Multiplying by 133.322 takes you from millimeters of mercury to pascals; multiplying by 0.007500637554192106329 brings you back.
Put in words: one millimeter of mercury equals 133.322 pascals, so the millimeter of mercury is the larger unit of this pair. Converting between them never changes the amount of pressure being measured — only the size of the unit you count it in.
A millimeter of mercury (mmHg) is a manometric unit of pressure.
It was historically defined as the pressure generated by a column of mercury exactly one millimeter high.
Today, it is most famous as the unit used in medicine for measuring blood pressure. It is also commonly used in meteorology, aviation, and physics to measure atmospheric pressure or vacuum pressure.
The mmHg unit originates from the invention of the barometer by Evangelista Torricelli in 1643.
Torricelli's device measured atmospheric pressure by seeing how high it could support a column of mercury in a tube.
Standard atmospheric pressure was found to support a column approximately 760 mm high, which established 760 mmHg as a standard reference point.
The most well-known application of mmHg is in medicine.
Blood Pressure: Readings are given as two numbers: systolic pressure (when the heart beats) over diastolic pressure (when the heart rests), such as 120/80 mmHg. This is a critical vital sign for human health.
Meteorology: Used for reporting barometric (atmospheric) pressure, which helps in weather forecasting.
Physics & Engineering: Used for measuring vacuum pressures and other low-pressure systems where precision is needed.
While mmHg is common, other pressure units are standard in different fields. Here are the most common conversions:
A pascal (Pa) is the standard unit of pressure in the International System of Units (SI). It is a derived unit, meaning other base units define it.
The primary pascal definition is one newton of force applied over an area of one square meter (1 Pa = 1 N/m2).
Because a single pascal represents a very small amount of pressure, it is most often seen in multiples.
The most common multiples are the kilopascal (kPa), equal to 1,000 pascals, and the megapascal (MPa), equal to 1,000,000 pascals.
These units are widely used in fields from weather forecasting to material science.
The pascal (Pa) unit is named in honor of Blaise Pascal, a key 17th-century French mathematician, physicist, and inventor.
His groundbreaking work on how fluids behave under pressure (known as hydrodynamics and hydrostatics) and his formulation of Pascal's Law were essential to our modern understanding of pressure.
To understand just how small a single pascal is, here are two real-world examples:
This shows why, for most everyday measurements (like tire pressure or weather), the larger kilopascal (kPa) is much more practical.
Here are some quick reference conversions from millimeter of mercury (mmHg) to pascal (Pa):
| millimeters of mercury | pascals |
|---|---|
| 0.000001 mmHg | 0.000133322 Pa |
| 0.001 mmHg | 0.133322 Pa |
| 0.1 mmHg | 13.3322 Pa |
| 1 mmHg | 133.322 Pa |
| 2 mmHg | 266.644 Pa |
| 3 mmHg | 399.966 Pa |
| 4 mmHg | 533.288 Pa |
| 5 mmHg | 666.61 Pa |
| 6 mmHg | 799.932 Pa |
| 7 mmHg | 933.254 Pa |
| 8 mmHg | 1066.576 Pa |
| 9 mmHg | 1199.898 Pa |
| 10 mmHg | 1333.22 Pa |
| 20 mmHg | 2666.44 Pa |
| 30 mmHg | 3999.66 Pa |
| 40 mmHg | 5332.88 Pa |
| 50 mmHg | 6666.1 Pa |
| 100 mmHg | 13332.2 Pa |
| 1000 mmHg | 133322 Pa |
| 10000 mmHg | 1333220 Pa |
Engineering datasheets across Europe write millimeter of mercury to pascal several different ways. The calculation is the same in every one of them.
| Language | Written as | Unit names |
|---|---|---|
| French | mmHg en Pa | millimètre de mercure → pascal |
| Spanish | mmHg a Pa | milímetro de mercurio → pascal |
| Dutch | mmHg naar Pa | millimeter kwikdruk → pascal |
| German | mmHg in Pa | Millimeter Quecksilbersäule → Pascal |
| Polish | mmHg na Pa | milimetr słupa rtęci → paskal |
For all Pressure converters, choose units using the From/To dropdowns above.