How to Convert Millimetres of mercury to Kilopascals (mmHg to kPa)
Pressure conversions are used for tyre pressure (psi or bar), blood pressure readings in mmHg and weather maps in millibars. This guide shows how to convert millimetres of mercury into kilopascals by hand, with examples and a quick-reference table.
The conversion
To convert millimetres of mercury to kilopascals, multiply the value by 0.133322. To go the other way, divide by the same number (or multiply by 7.5006375542). For a quick estimate, multiply by about 0.13.
Kilopascals = millimetres of mercury × 0.133322
Worked examples
- 3 mmHg = 0.399966 kPa
- 12.5 mmHg = 1.6665 kPa
- 75 mmHg = 9.9992 kPa
Millimetres of mercury to Kilopascals table
| Millimetres of mercury | Kilopascals |
|---|---|
| 1 mmHg | 0.133322 kPa |
| 2 mmHg | 0.266644 kPa |
| 5 mmHg | 0.66661 kPa |
| 10 mmHg | 1.3332 kPa |
| 20 mmHg | 2.6664 kPa |
| 25 mmHg | 3.3331 kPa |
| 50 mmHg | 6.6661 kPa |
| 100 mmHg | 13.3322 kPa |
| 250 mmHg | 33.3305 kPa |
| 500 mmHg | 66.661 kPa |
| 1,000 mmHg | 133.322 kPa |
Common questions
Is mmHg to kPa exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Kilopascals to Millimetres of mercury converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
Unit conversion is simply multiplication by a fixed ratio. The ratio between two units of the same quantity never changes, so once you know it you can convert any value in either direction.
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For any value, use the Millimetres of mercury to Kilopascals Converter or browse all pressure converters.
Run your own numbers: Millimetres of mercury to Kilopascals Converter