How to find total measurement of a mesh

So I know how to measure like a single mesh edge in edit mode, using the overlay, but I need to know the total length of my entire mesh. The whole thing. Not an individual edge, just the whole entire mesh (and it’s a complex model so it’d be a bit difficult to use the measure tool).

If you mean surface area of all triangles of a mesh, then MeshLab can do this.

I meant more the length on a singular axis. Like how many meters from end to end of the mesh. Not surface area.

How I measure mostly is by getting a simple shape and then scaling it. I use these shapes as placeholders which is useful for visual and snapping purposes also.
Shapes can be anything, cubes, planes, or even straight lines (eg: plane with merged vertices on a single axis) as long as the line has the equivalent scale of the plane towards a direction.

2020-01-14 09_10_38-Blender

If I want for example to set the height of a model to 4.65m I set the dimensions straight away to the template model. Also minding the origin points as well because if the origin point is in the middle it will be a huge trouble positioning the model on grid later on. I never set the origin to middle (unless is really needed).

I find also that the measurement tool is quite interesting for visualizing the numbers. However a huge problem is that I can’t set direct values to the control points, so in that sense I just roll with template models first and then snap the measurement tool to these versions.