Pressure (or stress) has the dimension mass per length time squared. The SI unit of pressure is the pascal, which is defined as a newton per square meter, or a kilogram per meter second squared.

Maple knows the units of pressure listed in the following table.

An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively.  Refer to a unit in the Units package by indexing the name or symbol with the context, for example, pascal[SI] or mmHg[standard]; by using an abbreviation, for example, at; or, if the context is indicated as the default, by using only the unit name or symbol, for example, pascal or mmHg.

The units of pressure are defined as follows.

A bar is defined as $100000$ pascals.

A standard atmosphere is defined as $101325$ pascals.

A technical atmosphere is defined as a kilogramforce per square centimeter, that is, $98066.5$ pascals.

A barye is defined as a dyne per square centimeter.

A pieze is defined as a sthene per square meter.

A torr is defined as $\frac{1}{760}$ standard atmosphere.

A vac is defined as a millibar.

A pound per square inch is defined as a poundforce per inch squared.

A planck pressure is defined as a planck mass per planck length per planck time squared.

$\mathrm{convert}\left('\mathrm{Pa}'\,'\mathrm{dimensions}'\,'\mathrm{base}'=\mathrm{true}\right)$

$\frac{\mathrm{mass}}{\mathrm{length}{\mathrm{time}}^2}$

$\mathrm{convert}\left(42.0\,'\mathrm{units}'\,'\mathrm{inHg}'\,'\mathrm{mmHg}'\right)$

$1066.800000$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{inHg}\left[\mathrm{`32degF`}\right]'\,'\mathrm{inH2O}\left[\mathrm{`39.2degF`}\right]'\right)$

$13.59544246$

$\mathrm{convert}\left(1.0\,'\mathrm{units}'\,'\mathrm{at}'\,'\mathrm{atm}'\right)$

$0.9678411054$

$\mathrm{convert}\left(1.231\,'\mathrm{units}'\,'\mathrm{bar}'\,'\mathrm{atmosphere}'\right)$

$1.214902541$

$\mathrm{convert}\left(34.21\,'\mathrm{units}'\,'\mathrm{pieze}'\,'\mathrm{torr}'\right)$

$256.5961017$