Area measurements

Hello Community,

I am trying to measure the area of a model to calculate the amount of finishing material (wood lacquer and paint) so I go to the context menu/sub-menu area. I get three different options: selection, layer and material.
the first gives me a totally different area than the other two. After that I made a test with a simple draw of a rectangle 120X240 cm; again I get two different readings on the area when it should be only one…


Experimenting with a simple test model is an excellent way to learn.
If you’ll upload the model file we can explain what you’re seeing.


Here it goes Geo,

Cambiador_david.skp (31.0 KB)

I hope this is clear enough.
Feel free to ask followup questions.

Options for Context Menu > Area

• Area of a Selection
Select one or more faces.
This option displays the area of the selected faces.
This option applies only to selected geometry in the current modeling context.
It does not apply to the face area of selected Groups or Components.

• Area by Layer
Select one face.
This option displays the area of ALL faces in the model assigned to the same layer as the selected face.

• Area by Material
Select one face.
This option displays the area of ALL faces in the model bearing the same material as the selected face.

A Face has two material attributes. Use Area by Material with caution!
A Face has a front side and a backside and each side has its own unique material attribute.
Paint “Red” on both front and back of a 1m x 1m face.
Area > Material for “Red” material = 2m sq. not 1m sq.

Groups and Components have one material attribute.
When a Group or Component is painted from outside its context, ALL default material faces (FRONT and BACK) within the context of the group display the group’s material attribute.
Model a cube 1m x 1m x 1m
Select the cube > Make Group
Paint the Group with “Red” material (from outside)
Materials Browser > In Model > Context click on “Red” material > Area = 12m sq. not 6m sq.

You can investigate this by viewing the material attributes of the Group and faces within the Group in the Entity Info box.

All your components are painted from outside.

Thus, Area > Material = The sum of all default faces (front and back) inside the components.
Re-paint the Components with the Default material.
Then edit each component and paint the individual faces within them.



What do you mean by “context” and outside that “context”?

Context meaning Separate Environment

Your model is comprised of eight components.
When you double click on a component you enter the editing context of the component.
The environment within a Group or Component is separate and completely isolated from other groups and the overall context (environment) of the model.

Everything inside the bounding box is within the context (environment) of the component.

I notice part of the problem with the model you shared is that one end (lateral) is a component and the other end is raw geometry.


I got it.
See, I am new to sketchup and so far I mostly do basic geometry models. I am a woodworker, so most of my models require measuring the area to know how much material would I need to do the finishing process (laquer, paint, varnish, etc.), so far I have been doing this the old fashion way with a measuring tape and a piece of paper.
May be I shoul keep on learning the basic stuff before I move to more complex matters…

Thanks for your time and knowledge Geo


It’s a very good model.
Area by material can be confusing even to experienced users at times.
To be accurate, it requires careful use of the Paint Bucket on faces, not on the outside of groups.


Additionally, if you paint both sides of a face or paint a component from “the outside” the material area calculation displays the area sum with both sides of the face included.


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I thought that in order to paint my models all I had to do is select everything and then just point with the paint bucket at any part of the model and voila, is it like that?

I used ThomThoms selction toys tool set, exploded everthing , selected all and then selected only faces. The entity info then reports 98 faces and 43726.7561.7561 cm^2. when you select the entity info tool it will show the front and back faces, or just 1 dpending if you are in the edit context or out side and shows the painted colors. You can also change them from there.