# Torr

**Torr**, a unit of pressure. One torr was originally defined as the pressure exerted by a millimeter depth of mercury (mmHg), then as 1/760 of a standard atmosphere.

Because the standard atmosphere is now a defined quantity in the SI system of units, the torr is hence defined as exactly 101325 / 760 pascals. Although the torr is still in common use in low-pressure engineering, the pascal is now the recommended unit of pressure.

The torr unit is named after Evangelista Torricelli.

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