Convert Pressure from kilopascals to millimeters of mercury (kPa to mmHg)

Kilopascal to Millimeter of Mercury Conversion Formula

To convert a pressure from kilopascals (kPa) to millimeters of mercury (mmHg), multiply by 7.5006.

• mmHg = kPa × 7.5006

The conventional millimeter of mercury is defined as exactly 133.322 Pa, and dividing 1,000 by 133.322 gives 7.50064. For mental arithmetic, 1 kPa ≈ 7.5 mmHg is accurate to better than 0.01%, and the atmosphere anchors the scale: 101.325 kPa = 760 mmHg.

Step-by-Step Example

A physiology paper reports an oxygen partial pressure of 13.3 kPa, and a clinician used to conventional units wants it in mmHg:

1. Take the pressure: 13.3 kPa
2. Multiply by 7.5006: 13.3 × 7.5006 = 99.8 mmHg

The reported value is simply normal arterial PaO₂ (~100 mmHg) written in SI.

Quick Reference Table

Translating SI Back Into Mercury

Most conversions modernize old units into SI; this one runs the other way, because two large professions still think in mercury. Medicine is the first: blood pressure cuffs, ventilator readouts, blood-gas reports in North America, and every clinician's memorized normal ranges (120/80, PaCO₂ 40) are mmHg, so SI-formatted values from European journals and laboratory systems get multiplied by 7.5 before intuition can engage. Vacuum technology is the second: rough-vacuum work quotes torr — identical to mmHg for practical purposes — so a process chart specifying 2.5 kPa becomes about 19 torr at the pump gauge. The factor 7.5 is friendly enough that estimation usually suffices, and the two round anchors (100 kPa ≈ 750 mmHg, 13.3 kPa ≈ 100 mmHg) bracket nearly every realistic value in both fields. One caution when precision matters: mmHg is defined via mercury's density at 0 °C under standard gravity, so a mercury column at room temperature reads about 0.3% off the conventional unit — negligible clinically, but relevant when calibrating barometers.

How many kilopascals are in one millimeter of mercury? One millimeter of mercury (mmHg) contains 0.133322 kilopascals (kPa) — the inverse of the factor above. Multiplying by 7.500637554192106329 takes you from kilopascals to millimeters of mercury; multiplying by 0.133322 brings you back.

Put in words: one kilopascal equals 7.500637554192106329 millimeters of mercury, so the kilopascal 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.

What is a kilopascal (kPa)?

A kilopascal (kPa) is a metric unit of pressure that equals 1,000 pascals.

It is one of the most common units for measuring pressure worldwide, used in both scientific and everyday applications.

The Kilopascal (kPa) Explained

The base unit, the pascal (Pa), is named after the French polymath Blaise Pascal.

As part of the metric system (also known as the SI system), the kilopascal is widely used in scientific, engineering, and industrial fields due to its standardization and ease of calculation.

Common Applications of Kilopascals (kPa)

The kPa unit is used to measure pressure in many everyday and technical contexts. Common examples include:

• Tire Pressure: A common measurement for vehicle tire pressure in many countries outside the US.
• Weather Forecasting: Used for reporting atmospheric pressure.
• HVAC Systems: Essential for measuring differential pressure in heating, ventilation, and air conditioning systems.
• Medical: Frequently used for measuring blood pressure.
• Manufacturing: Critical for monitoring pressure in various industrial processes.

Kilopascal Conversions (kPa to PSI and Bar)

For practical use, it's essential to understand how kPa converts to other common pressure units.

• kPa to PSI: 1 kPa is approximately 0.145 PSI (Pounds per Square Inch). PSI is the standard pressure unit used in the United States.
• kPa to Bar: 100 kPa is exactly equal to 1 bar. The bar is another metric unit frequently used for atmospheric and water pressure.

What Is a Millimeter of Mercury (mmHg)?

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 Origin of the mmHg Unit

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.

Common Applications of mmHg

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.

How to Convert mmHg to Other Pressure Units

While mmHg is common, other pressure units are standard in different fields. Here are the most common conversions:

• 1 mmHg = 133.322 pascals (Pa)
• 1 mmHg = 0.133322 kilopascals (kPa)
• 760 mmHg = 1 standard atmosphere (atm)

kilopascal to millimeter of mercury Conversion Table

Here are some quick reference conversions from kilopascal (kPa) to millimeter of mercury (mmHg):

This conversion in other languages

Engineering datasheets across Europe write kilopascal to millimeter of mercury several different ways. The calculation is the same in every one of them.