The diagram below shows the approximate operating ranges of some commonly available pressure and vacuum measuring instruments. The pressure scale shown ranges from the degree of vacuum found in interplanetary space (and some vacuum processes on Earth) to pressures that are higher than experienced at the bottom of deep ocean trenches (and in hydraulic systems) - some seventeen orders of magnitude.

Pressure-vacuum scale, measuring instruments and pressures in the environment

The diagram is only meant as a general guide and is not a rigorous classification but it does illustrate the range of technologies used to measure pressure (or sometimes generate it), where particular pressures might be found in nature and the continuity of pressure with vacuum. Its single scale includes absolute-, differential- and gauge-mode pressures that are denoted with A, D or G flags respectively.

Atmospheric pressure is nominally 10⁵ Pa (100 000 Pa, 1 000 hPa, 1 000 mbar) and this value is shown about three quarters of the way from the left-hand side of the scale. It is interesting to note that, on this logarithmic scale, there are many more pressure measurement decades below atmospheric pressure than above it.