Learning Blender after SketchUp: precise measurements

Show edge lengths in the viewport

When I work on 3D-print projects, where a millimeter matters, I basically always keep edge lengths on screen. To switch them on, drop into Edit Mode, open the Overlays menu in the top-right corner of the viewport, and near the bottom you will find a group of checkboxes for measurement display. Tick Edge Length.

Now selecting any edge shows its length. Select a whole face and it shows the length of every edge around it, and you can add more with Shift+click. The numbers update live as you reshape geometry, so you always know the real size of what you are building.

Choose your units and how they display

Open the Scene Properties tab in the Properties panel (bottom-right by default) and look under Units. There is more here than a simple metric-or-imperial switch, and it is worth setting up once:

• Unit System: Metric by default, or Imperial, or None for raw Blender units (where one unit is one meter).
• Separate Units: splits a value into parts, so 22.6cm shows as 22cm 6mm. Genuinely helpful in imperial, where 1.95 feet is awkward to picture.
• Rotation: degrees (default) or radians.
• Length: the base unit to keep readings sane. Designing a bolt? You want 2.3mm, not 0.0023m. A building should not read as 24,000 centimeters.
• Unit Scale: rescales the whole workspace. The default starting cube is 2 meters. For 3D printing I set Unit Scale to 0.1 in metric, which makes that cube 200mm, a far friendlier size to model prints at.

Save your settings as the default

Setting units on every new project gets old fast, so bake them in. Go to File, then under Defaults choose Save Startup File, and confirm. From now on every new project opens with your units, your unit scale, and any other tweaks (like clip start) already set. It is the single best five-second habit for precision work.

Type exact measurements as you work

This is the one that feels most like SketchUp. During any transform, a grab, rotate, or extrude, just start typing a number. As you type, the value appears in the top-left corner above the toolbar, and Blender interprets it against your unit system and base length. So mid-extrude you can type 25 and, with millimeters as your base unit, pull exactly 25mm. Press Enter or left-click to commit. Combined with axis constraints from Part 1, that is precise modeling with almost no menus.

Measure anything with the Measure tool

For checking distances without changing anything, Blender has a Measure tool in the left toolbar, its own tape measure. Click and drag from one point to another to read the distance, and hold Ctrl to snap the ends to vertices or edges for an exact reading.

• Reposition or delete: hover an endpoint until you see the four-triangle cursor, then drag it, or press Delete to remove it.
• Measure an angle: click the midpoint of a measurement line to turn it into a protractor.
• Measure thickness: hold Shift and the right mouse button to measure straight across segments of the model.

You can leave as many measurements on the model as you like, but they only show while the Measure tool itself is active, so they never clutter your normal working view.

Next: a dimension tool for Blender

Between the overlay, proper units, typed input, and the Measure tool, Blender handles precise work as well as anything, once you know where the settings live. Set them once, save your startup file, and it is precision from then on.

I know a lot of you are itching for one of SketchUp's best tools: Dimensions, the kind that annotate a drawing. Blender has no built-in match, but we can get close with a custom add-on. That, plus how to install add-ons in the first place, is Part 4.5.