Precise dimensions

Hi All,

First off, I apologize if this has been covered often but I’m having trouble reaching absolute dimension values for a very simple project.

I’ve read through some tutorials on using the scale and the tape measure tool but try as I might I cannot get the 2x4’s in this project to 30" length. (it always becomes greater or less than)

The last thing I tried was setting a guideline by measuring 30" off the mid-point of the 2x4 and then scaling the object to snap to that line, but still no dice. I’m sure it’s user error but any advice would be much appreciated.


4Runner_Bed_Platform_Simple_2021.skp (84.7 KB)

Are you just trying to drag out the rectangle and hope you get it the correct size or are you actually typing in the dimensions?

Good question. I’m typing the calls into the measurement box at 30”. Something happened and they were knocked out of spec which is why I’m trying to resize them.

I realize that it’s such a simple object that starting over would be easy but I’m stuck on how I can’t seem to fix the dimension after the fact and get it to be exact.

Are there tricks to doing this?

Thanks for the fast response by the way!

The only thing I can think of would be that you are clicking in the measurements window which you shouldn’t be doing. If you are doing that, you would be shifting the focus away from the model space and the thing you are drawing.

The steps are:

  1. Start the rectangle tool (press the r key).

  2. Orient it in the direction you want (use arrow keys to force the axis Right for red axis, Left for green direction, Up for blue direction, Down for parallel to edge or at right angles to edge).

[If you don’t use an arrow key, SU will draw in the plane it is most nearly ‘looking at’. So if you are mostly looking down from the top, and start over an empty background it will draw on the x-y (red-green) plane. If you are looking mainly from the front, it will draw in the x-z (red-blue) plane, and if from left or right, in the y-z (green-blue) plane]

  1. Click on the start point, then move the mouse in the direction you want but don’t worry about how far

  2. Type the width and thickness of the beam, separated by comma (US and most English speaking countries) or semicolon (most European countries or non-English versions of SU), then press Enter key. The dimensions may draw in the wrong order, in which case just type again swapping the first and second dimension. The dimensions will appear in the measurement box

  3. Select the rectangular face you have just drawn if it isn’t already selected, then press the p key to start the PushPull tool, and click at the start of the length you want to draw. That doesn’t have to be on the rectangle, but can if you wish start on some other inference point from which you want to infer the length

  4. Type the length (30" for example or 2'6), and press Enter key to finish, or click on an inference point at the length you want, so it fits some other part you have already drawn. Don’t move the mouse before you press Enter - if you do, that may be why you are not getting the exact length or dimensions you typed


If you are mainly drawing rectangular beams or similar objects, try the free Wood Framing plugin from the SketchUcation Plugin Store. That will draw your piece as a named component in as little as three clicks once you have chosen its width and thickness.

Here’s a direct link to it.

If you haven’t previously registered you will need to create a (free) account first, before you can download the plugin and install it.

Thank you Dave and thank you John! Very much appreciated.

I also installed the plugin you noted John. Very cool stuff!

I created this simple 1.5",3.5",30" board. But then when I try to scale it down to 25" in length by snapping to a guideline that was manually entered at 25" in the measurement box it gets close, but not precisely at 25". (25 13/64") Is that to be expected and/or am I doing something incorrectly? (likely :slight_smile: )

Thanks in advance!

Dave D

Did you leave Length Snapping enabled?

If you must use the Scale tool, why not just enter the final dimension you want making sure to include the units. Or you could use Push/Pull or Move to take the 5 inches off.

Keep in mind that Scale will be inappropriate if you want to change the length of a “board” that has details such as tenons, mortises or other holes or anything else that makes it not a simple rectangular prism.

Thanks Dave! I was finally able to get the move function to resize properly based on your capture.

In the last part of this clip I tried to manually enter the new dimension at 25" for the scale tool but I notice as soon as I hit the shift key to enter the unit (") it acts as a modifier and overwrites my entry. (you can see in the clip below at about 48 seconds.)

I have default settings including no length snapping but should I have changed anything in particular?


Thanks again for your patience!

Your units look good.

As for scaling, try click and release on the handle, move the handle, click and release again, then type the 25 followed by Shift+" and hit enter.

Oh my. That was it. I was banging my head against the wall there.

Many thanks! :slight_smile:

Should I feel sorry for the wall? :crazy_face:

Most operations in SketchUp are a click and release to start followed by a click and release to end. Once you make the second click and release you can enter the precise value.

Not what you were doing in the clip, but if you use the plugin, then resize a piece made with it, you need manually to edit the component name, which uses the length dimension as part of the name.

That makes sense. Thanks John!

Out of curiosity, do you have a specific project in mind that you are working on?

Honestly, I wasn’t just starting with a super simple wood bed platform for the back of my 4runner to level it out.

Thought it could be a good start in becoming acquainted with Sketchup for various potential future projects. (Thinking wood and possibly 3D printing)

It’s been ~20 years since I really used any sort of CAD program so I’m really starting all over. My high school was fortunate enough to get computers and AutoCAD for our drafting/shop classes but oh that’s been a while. :stuck_out_tongue_winking_eye:

So one thing that I’ve found useful for creating accurate and precise models is to model as much as possible in place. Set components where they will live and create additional components to fit.

This is a model I did recently for Fine Woodworking Magazine. I created the front left leg and made it a component. Then I copied the leg to make the other three placing them exactly where they need to be. After that I created the apron components in place between the legs. With the legs properly placed there’s no need to actually know the shoulder to shoulder distance for the aprons. I didn’t bother with laying out the mortises in the legs. I added the tenons on the ends of the aprons and used them to cut the mortises. That’s something I wish I could do in the shop. There’s an applied bead molding near the bottoms of the aprons. They were modeled in place and then they were used to cut the grooves they lay in on the aprons and the dadoes in the legs. The top started as a rectangle drawn on top of the legs using the outside corners of diagonally opposed corners. After extruding it to thickness using Push/Pull, I then pulled out the edges to the width of the overhang. This resulted in the top being positioned exactly centered on the legs as it was supposed to be. The only things I needed to know to create the top, then were the thickness and the amount of the overhang. I let SketchUp tell me how big the top is.

Anyway, it’s all very simple and results in precise models.


This is very cool! (and makes the things I’m trying to do at the moment seem incredibly simplistic. But, got to start somewhere I suppose :smiley: )

Thanks for sharing the design methodology you use within SketchUp. I can see how that would make it much easier to get to a precise model while leveraging SUs strengths.

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