Changing Units in SketchUp, Basic Settings and Drawing Logic

Ufuk ŞEN

October 24, 2026Updated: November 9, 20265 min read2

Knowing how to change units in SketchUp is the first thing you need before you start drawing. If you start with the wrong unit, every value you type comes out different from what you expect. In this lesson we switch the units to centimeters in Model Info, then introduce the axes, the human figure and the Line tool. It is a core lesson for beginners who want to get SketchUp’s drawing logic down.

Changing Units in SketchUp, Basic Settings and Drawing Logic

We recorded this lesson in 2015 as the third part of our basic tutorial series. I’m Ufuk Şen, and in this series I teach SketchUp from the very beginning. The look of the windows has changed a little in newer versions. But where the units setting lives and the drawing logic have stayed the same. (The video is in Turkish; this guide walks through the key steps in English.)

In this video

Changing units with Window > Model Info > Units
Why the settings windows have no OK button
What the red, green and blue axes mean
The scale role of the human figure on screen
First lines with the Line tool and the closed-face logic

Where do you change units in SketchUp?

To change the unit, we open the Model Info window from the Window menu. From the list on the left, we go to the Units section. Here you see options such as meters, centimeters and millimeters. When you choose centimeters, for example, the drawing dimensions switch to centimeters right away.

We work in centimeters in our lessons. For interior and furniture dimensions, centimeters are both readable and practical. But you can choose a different unit depending on the type of your project. What matters is making this decision before you start drawing.

How are the settings saved?

There is a small detail that surprises new users. You won’t find an OK or Save button in the Model Info window. Don’t worry, though: the settings take effect the moment you change them. Just close the window with the X in the top-right corner.

SketchUp units and axes

If you come from another 3D program, the axes may confuse you at first. SketchUp solves this very simply. There are three axes on screen: red, green and blue. The red and green axes show the ground, and the blue axis shows height.

These axes set our drawing directions. As long as you draw along them, you never lose your bearings. Also, when a line you draw is parallel to an axis, it takes on that axis’s color. This makes working with exact dimensions easier.

Why is the human figure there?

When you open a new file, you see a human figure in the scene. To see the figure’s information, select it and look at the Entity Info panel. The figure represents someone from the SketchUp team and changes from version to version.

Its real job is scale control. The figure is about 1.70 m tall. You check a door or window you draw by comparing it with the figure. If you delete the figure and work without dimensions, you end up with an out-of-proportion model. This mistake comes back to bite you in both modeling and rendering. We also explained why working to scale matters in our why working with exact dimensions matters article.

The Line tool: start with a line, finish with a line

Now we move on to one of the most important tools: Line. Line is the basic command in every drawing program. Among ourselves we say it like a proverb: “Start with a line, finish with a line.” In other words, the foundation of a 3D model is always the line.

In the video we pick the Line tool and draw a few lines along the axes. The moment we close the lines, a face forms between them. Then we hold down the middle mouse button and rotate the view with Orbit. That way we see the face we drew from different angles.

At minute 4 of the video, we point out a detail. Because we are looking at the screen from above, the first line doesn’t start at the axes’ origin. So we delete the line and draw it again from the origin.

Why does a closed face matter?

In the video we draw a square by eye, without typing values. So we get a square with rough dimensions. But the key point is creating a closed face. Lines that don’t close don’t create a face.

Without a face, you can’t give an object depth. You can’t push it up with Push/Pull, and the model doesn’t become 3D. A face needs at least three points to join. This rule is the foundation of all modeling in SketchUp.

First steps after setting SketchUp units

After you set the unit and get to know the Line tool, the other basic commands come next. In the next lessons we show how to draw by typing dimensions and reinforce this knowledge with examples. You can find the whole series in our SketchUp basics tutorial set. We also explained how to bring a plan to the correct scale in our plan scaling lesson. For official information on unit options, see the SketchUp Help Center page.

Summary

The SketchUp units setting is at Window > Model Info > Units. We work in centimeters, and settings take effect the moment you change them. The red, green and blue axes set your drawing direction. The human figure helps you keep proportions. When the lines you draw with the Line tool close, a face forms and the model is ready to go 3D.