How can I check if a line is parallel with an axis?

I know I can check if a line is parallel to an axis by making 2 dimensions from a reference point (like the origin) to 2 different points on the line – if the 2 dimension values are the same, it is parallel to that line.

But the problem with this method is (1) it’s a bit awkward, and (2) if the line is actually aligned with the axis the dimension of zero length is a problem.

So, is there a simpler way?


Notice the inference color when the line is parallel to the axis. Look at the lower left of your screen to see tool options.

With practice you will find it becomes easier to ensure you are modeling on axis. Let the inferencing help you.

You might leverage the Tape Measure tool to check existing geometry. If you click on an axis line and drag out a guideline it will be parallel to the axis. You might need to zoom in a bit to confirm things.

@RLGL, I should have been more clear. As @DaveR guessed, I did mean existing geometry (since I know about using the green, red, and blue guides when drawing new lines, etc).

I meant situations where I’ve done a lot of work on a model rotating things and even moving individual parts of geometry to make needed small angles.

Like @DaveR I’ve tried to check for lines on existing geometry being parallel by drawing new lines very close to the line in question, and trying to stay along the axis as I draw. It doesn’t work well in my experience, even when zooming in and out.

I zoom in to see if things look like they are touching, but I found this to be unreliable. The magic SketchUp does to make a 2D screen look like it has 3D objects does not always work perfectly, so I want a simple yet reliable way to do this kind of check.

If not, I’ll just stick with the current work around I described using the dimension tool twice.

As I indicated, with practice you’ll find this isn’t a problem. The display is reliable although with the thick profile edges in the default style you might have to zoom in more to see possible errors if you’ve induced them. Choose a style with the Profiles off will make it easier. If you opt for SketchUp Go/Shop you can edit the styles which could useful.

Also make sure you turn off Length Snapping in Model Info and that you enter actual dimensions or angles when moving and rotating stuff. It also helps to prevent errors if you do as much of your modeling in place using existing objects for reference.

But it does! Where do you see an imperfection in the model you work with on screen? Please explain.

Btw the ‘Tape measure’ tool shows coordinates x,y,z when hovering over endpoints. Set precision to max and compare what the cursor shows.


Your “by the way” answers my question. It’s not perfect, but it’s much simpler than my work-around using the dimension tool twice.

To summarize: I need to hover the Tape Measure tool over the 2 ends of the line and note the relevant x, y, z coordinate. The reason I say “It’s not perfect” is that I see no way to copy those coordinate values so that I could easily compare them. With the max precision you mentioned that’s a lot of digits - 10 digits per coordinate in the example I provide below.

To deal with things like this I typically take screen shots, but you can’t do that because SketchUp causes the coordinates to disappear when I press the keys to take a screenshot. So I found an alternative: I make a screen recording, as shown in the animated .gif below


You could use the Text tool to place labels with the coordinates.

I presume you are using this in your hobby. What exactly are you modeling and how much precision do you really need. SketchUp is capable of the precison but maybe you don’t need the highest precision in the end.

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Thanks @DaveR – this is even better than using the Tape Measure tool because the coordinates stay on screen so you can easily compare them. Just what I needed! If I could give both you and @Wo3Dan credit for the solution to my question, I would, but he was first.

Thanks again for all the help.

And this happens to me all the time :wink:

I just look at the final three or four digits. If they match, then I pay attention to additional digits (though if the last few digits match then it is very likely that the entire number will match).

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