How to Make Your SketchUp Model Accurate

By Aidan Chopra

It’s all well and fine to make a model, but most of the time you need to make sure that it’s accurate — that what you’ve modeled is precisely the size you intend it to be. The key to accuracy in SketchUp is the little text box that lives in the lower-right corner of your SketchUp window.

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This box is the Measurements box, and here are some things you can do with it:

  • Make a line a certain length.

  • Draw a rectangle a certain size.

  • Push/pull a face a certain distance.

  • Change the number of sides in a polygon.

  • Move something a given distance.

  • Rotate something by a certain number of degrees.

  • Make a certain number of copies.

  • Divide a line into a certain number of segments.

  • Change your field of view (how much you can see).

Here’s what you need to know about the Measurements box:

  • You don’t have to click in the Measurements box to enter a number. This one’s a big one: SketchUp beginners often assume that they need to click in the Measurements box (to select it, presumably) before they can start typing.

    You don’t have to click it — just start typing, and whatever you type shows up in the box automatically. When being precise, SketchUp always “listens” for you to type something in this box.

  • The Measurements box is context-sensitive. What this box controls depends on what you happen to be doing at the time. If you’re drawing an edge with the Line tool, it knows that whatever you type is a length; if you’re rotating something, it knows to listen for an angle.

  • You can set the default units for the Measurements box and override the default when needed.

    • You don’t need to type a unit if you want to use the default unit. Perhaps you want a line you’re drawing to be 14 inches long. If inches are your default unit of measurement, just type 14 into the Measurements box and press Enter — SketchUp assumes that you mean 14 inches.

    • Do type a unit if you want to override the default unit. For example, if you default is inches and you want to draw something 14 feet long, type 14′, just to let SketchUp know that you mean feet instead of inches. You can override the default unit of measurement by typing any unit you want. If you want to move something a distance of 25 meters, type 25m and press Enter.

    • You set the default units in the Model Info dialog box. You can open this dialog box from the Window menu. Open the Units panel, and choose your new default unit from the drop-down menu.

  • Sometimes, the Measurements box does more than one thing. In certain circumstances, you can change its mode (what it “listens for”) by typing a unit type after a number. For example, when you draw a circle, the default “value” in the Measurements box is the radius — if you type 6 and press Enter, you end up with a circle with a radius of 6 inches.

    But if you type 6s, you’re telling SketchUp that you want 6 sides (and not inches), so you end up with a circle with 6 sides. If you type 6 and press Enter, and then type 6s and press Enter again, SketchUp draws a hexagon (a 6-sided circle) with a radius of 6 inches.

  • The Measurements box lets you change your mind. As long as you don’t do anything after you press Enter, you can always type a new value and press Enter again; there’s no limit to the number of times you can change your mind.

  • You can use the Measurements box during an operation. In most cases, you can use the Measurements box to be precise while you’re using a tool. Here’s how that works:

    1. Click once to start your operation (such as drawing a line or using the Move tool).

    2. Move your mouse so that you’re going in the correct color direction. Be sure not to click again.

      If you’re using the Line tool and you want to draw parallel to the green axis, make sure that the edge you’re drawing is green.

    3. Without clicking the Measurements box, type the dimension you want.

      The dimension appears in the box.

    4. Press Enter to complete the operation.

  • You can also use the Measurements box after an operation. Doing this revises what you’ve just done.

    1. Complete your operation.

      This may be drawing a line, moving something, rotating something, or any of the other things mentioned.

    2. Before you do anything else, type whatever dimension you intended and then press Enter.

      Whatever you did is redone according to what you typed.

To give you a more concrete example, say you want to move the box, as shown in the figure, a total of 5 meters in the red direction (parallel to the red axis).

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Here’s what you do:

  1. With the Move tool, click the box once to pick it up.

  2. Move your mouse until you see the linear inference that tells you you’re moving in the red direction.

  3. Type 5m and then press Enter. The box is positioned exactly 5 meters from where you picked it up.

  4. On second thought, you’re not happy with the 5 meters, so you decide to change it. Type 15m and then press Enter again.

    The box moves another 10 meters in the red direction.

  5. You can keep changing the box’s position until you’re happy (or bored).