Convert newton per square meter to pascal

Weather reports give air pressure in hectopascals or millibars (the two are identical): 1013.25 hPa is the standard atmosphere, and in the US inches of mercury (29.92 inHg) are used instead. Tyre pressure is quoted in bar in Europe and psi in the US and UK, 1 bar ≈ 14.5 psi. Blood pressure is measured in millimetres of mercury everywhere, 120/80 mmHg being the textbook value, and the torr is practically the same unit under another name.

The pascal is one newton per square metre, so small that engineering works in megapascals: 1 MPa is 10 bar or 145 psi. Strength of materials is quoted in it – concrete grade C25/30 withstands 30 MPa in a cube test, ordinary structural steel yields at 235 MPa and breaks at about 400 – and hydraulic systems run at 20–35 MPa. Stiffness needs gigapascals: steel's modulus of elasticity is about 210 GPa, aluminium's 70, concrete's 30 and timber's 10. The pressure at the centre of the Earth is some 360 GPa.