kPa to mmHg Conversion

How to use the kPa to mmHg conversion calculator

What this calculator does

This calculator converts one nonnegative pressure value between kilopascals (kPa) and millimeters of mercury (mmHg). It also reports the same physical pressure in pascals, bar, standard atmospheres, and inches of mercury. The result is an exact unit conversion based on fixed conversion constants; it is not a measurement, diagnosis, weather forecast, or recommendation about a safe operating pressure.

When to use it

Use the calculator when comparing a pressure specification written in kPa with a reading reported in mmHg, checking atmospheric-pressure values, translating laboratory or engineering documentation, or preparing a consistent pressure table for a worksheet. The units are especially common in science, meteorology, vacuum work, and clinical instrumentation, although any real-world decision should still follow the standards and procedures for that field.

How to calculate

1. The calculator opens with a ready-to-use example of 101.325 kPa, which is displayed as approximately 760.000 mmHg. The Excel download is available immediately for this example.
2. Replace the number in Pressure value with your own finite value. Use digits with an optional decimal point, such as 7, 35.5, or 101.325.
3. Choose either kPa or mmHg in the Pressure unit selector. Changing the unit converts the current value so the represented physical pressure stays the same.
4. Read the highlighted converted pressure, then review the equivalent-unit cards and table. Select Download Excel to export the current validated inputs and outputs as a real XLSX workbook.
5. Select Reset to clear the demonstration value and all calculated content. Reset may disable Excel export until a complete valid pressure value is entered again.

Input guide

Pressure value is required. It accepts a plain nonnegative decimal number using a period as the decimal separator. A realistic example is 101.325. Negative values are rejected because this converter is intended for absolute pressure magnitudes, and scientific notation or mixed text such as “1e3 kPa” is not accepted. Increasing the value increases every equivalent pressure proportionally.

Pressure unit is required and offers kPa or mmHg. Choose the unit that matches the number you are entering. A common mistake is to type a value measured in mmHg while leaving kPa selected, which changes the physical meaning by a factor of about 7.5.

Output guide

Converted pressure is the primary result in the unit opposite the selected input unit. Kilopascals and Millimeters of mercury show the canonical pair. Atmospheres and Inches of mercury provide commonly used comparison units. The Pressure equivalents table adds pascals and bar. Zero means zero pressure magnitude; larger results simply represent the same larger pressure in another unit. No output is an estimate: differences arise only from displayed decimal rounding.

Worked example

The startup example uses 101.325 kPa. Multiplying by the standard factor 7.500616827 gives 760.000 mmHg after display rounding. The same pressure is 101,325 Pa, 1.01325 bar, 1 standard atmosphere, and about 29.9213 inHg. This well-known equivalence is consistent with the NIST explanation of SI pressure units and the conventional definition of a standard atmosphere.

Learn more

The pascal is the SI derived unit of pressure, equal to one newton per square meter. For broader unit definitions and accepted symbols, consult the BIPM SI Brochure. For standard-atmosphere values used in technical work, the NIST Guide for the Use of the International System of Units provides authoritative conversion guidance.