Pressure measures the amount of force pushing against something perpendicularly, such as the amount of force a gas applies to the inner wall of tires. Pressure is measured using a variety of units, including megapascals (MPa) and Newtons per square millimeter (N/mm^2). You may need to convert from megapascals if you are filling a tire with air and the tire lists the needed pressure in MPa but your pump measures pressure in N/mm^2. Since the conversion factor equals one MPa to one N/mm^2, the conversion between units is easy.

Multiply the number of MPa by 1,000,000 to convert to Pascals. The prefix "M" in the metric system stands for "mega-," representing 1,000,000. For example, 2 MPa equals 2,000,000 Pa.

Switch the units from Pa to N/m^2 (Newtons per meter squared) because these two units are equivalent. In this example, 2,000,000 Pa would become 2,000,000 N/m^2.

Divide the number of N/m^2 by 1,000,000 to find the pressure in N/mm^2, since there are 1,000,000 mm in one meter. In the example, divide 2,000,000 N/m^2 by 1,000,000 to get 2 N/mm^2.