The grid is a ruler under the plan. With snapping on, every point you draw or drag lands on it, so edges come out at whole metres or half metres without careful mousework.
Turn snapping on
- Click Environment settings at the top of the sidebar.
- Under Grid, turn on Show grid if it is not already.
- Set a Step — 1 m for laying out a site, 0.5 m or 0.25 m for detail.
- Turn on Snap. The panel confirms: points snap to the nearest step of the grid as you move them.
Now draw a rectangle. Its corners jump from one grid point to the next, and its edge lengths read as round numbers.
Unit and origin
The same panel sets the unit the plan reads in (metres, centimetres or feet) and where the grid starts — an offset in X and Y, so its lines can align with a wall or a fence you have traced rather than the corner of the canvas.
When to switch it off
Snapping fights you when you are tracing a curved boundary from a photo, or placing a point that really is at 3.37 m. Turn Snap off for that stroke, or hold Shift, ⌥ or ⌘ while dragging a point to ignore the grid for that one move.
Grid lines are a separate setting
How the grid looks — line weight, colour, whether it draws behind or over the shapes — is under the small cog on the plan itself. That panel only changes the drawing; the step, unit and snapping are the environment settings above.
Next
Draw a polygon point by point — for any outline that is not a box.