Blacking out a concrete column on a plan, filling an arrowhead, filling a symbol: every 2D drawing has a few places that need a solid fill. The solid command in AutoCAD does that with a few point picks. It is quick, but it has a point-order trap that almost everyone falls into the first time.
"Solid" also means 3D solids in AutoCAD, which is easy to confuse. This article is about the SOLID command for flat 2D fills; 3D solids are in 3D solids in AutoCAD. Every test uses AutoCAD 2027 and the acadiso.dwt template, and the image above is made from real screenshots. For drafting taught properly, the Institute runs an AutoCAD course for construction.
Starting SOLID
Type SOLID or the alias SO, from the 2027 acad.pgp file. The command has no button on the default ribbon. The 2027 release asks:
| Step | The prompt | What you do |
|---|---|---|
| 1 | Specify first point: | First point |
| 2 | Specify second point: | Second point |
| 3 | Specify third point: | Third point |
| 4 | Specify fourth point or <exit>: | Fourth point, or Enter to stop at a triangle |
| 5 | Specify third point: | Pick more to add a piece, or Enter to finish |
The Autodesk documentation on SOLID describes it as creating solid-filled triangles and quadrilaterals. Press Enter at the fourth-point prompt for a triangle.
Z order: the bow-tie trap
The same 1000 × 1000 square, its four corners picked in two different orders:
| Order | Result |
|---|---|
0,0 → 1000,0 → 0,1000 → 1000,1000 (a Z) | A filled square |
2000,0 → 3000,0 → 3000,1000 → 2000,1000 (going round) | A bow tie: two triangles meeting at a point |
The habit when drawing shapes is to go round the corners, as with a polyline. With SOLID that gives a bow tie. The command joins point 1 to 2 and point 3 to 4, then fills between those two edges. For a square, the third point must be on the same side as the first, so you pick in a Z: bottom left, bottom right, top left, top right.
Triangles have no trap: pick 4000,0, 5000,0, 4500,1000, press Enter at the fourth point, and you get a filled triangle.
It helps to picture the command as filling a band between two edges rather than tracing a boundary. The first edge runs from point 1 to point 2 along the bottom of the square. The second edge runs from point 3 to point 4. When those two edges point the same way, left to right in both cases, the band between them is the full square. When the second edge points the other way, right to left because you went round the corner, the band twists into the bow tie, crossing itself exactly halfway up.
The same picture fits the continuation prompt. In the six-point example further down, every pair is picked left to right, 0,0 then 1000,0, 0,1000 then 1000,1000, 0,2000 then 1000,2000, and both pieces come out as clean rectangles, one from height 0 to 1000 and the next from 1000 to 2000. Keeping every pair in the same direction as the first is the whole trick.
FILLMODE: filled or outlines only
FILLMODE is 1 on the default machine. Set it to 0 and REGEN, and all three SOLID shapes show outlines only, as in the lower row of the image. The bow tie is then clearly two crossing triangles.
According to Autodesk, 2D solids are filled only when FILLMODE is on and the viewing direction is square to the solid. The variable also affects SOLID-pattern hatches: the hatched square on the right of the image becomes an outline too. So when fills suddenly show as outlines only, check FILLMODE first, before suspecting damage to the drawing. FILLMODE does not change the objects themselves: setting it to 0 and back to 1 leaves all four shapes exactly as they were, so the outline view is a safe way to inspect fills and spot a bow tie hidden inside a small symbol.
SOLID or a solid hatch
The other way to fill is a hatch with the SOLID pattern. A square filled with SOLID and a square of the same size filled with a solid hatch, placed side by side, and their properties read.
SOLID command | Hatch, SOLID pattern | |
|---|---|---|
| Object type | Solid | Hatch |
| Area readable | No area property | 1 000 000 |
| Needs a closed boundary drawn first | No, only points | Yes |
Outline only when FILLMODE is 0 | Yes | Yes |
| Point-order trap | Yes | No |
On screen they look identical, but the SOLID object has no area to read, while the hatch gives 1 000 000 at once. To measure filled areas, or to fill curved or many-sided shapes, use the hatch command. SOLID suits small triangular and four-sided fills: arrowheads, column symbols, level markers.
A 2D solid fill from the command line with a hatch
-HATCH, the command-line version, fills entirely from the keyboard, in four steps:
| Step | Type | Meaning |
|---|---|---|
| 1 | -HATCH | Command-line hatch |
| 2 | P, then SOLID | Choose the solid pattern |
| 3 | S, then select the boundary | Select an object as the boundary, such as a rectangle |
| 4 | Enter twice | Finish selecting and create the hatch |
A 1000 × 1000 rectangle from RECTANG, filled this way, gives a Hatch of 1 000 000, exactly its area. Unlike SOLID, a hatch fills any closed shape: round, curved, many-sided or with holes.
| Job | Better choice |
|---|---|
| Arrowheads, level triangles, small three- or four-sided symbols | SOLID |
| Columns, walls and cores blacked out on plans | Solid hatch |
| Curved, round or holed areas | Solid hatch |
| Areas you need to measure | Solid hatch |
Several pieces in one command
After the fourth point the command does not stop; it asks Specify third point: again. Pick two more points to add a quadrilateral joined to the last edge of the previous piece, still in Z order. Press Enter at the third-point prompt to finish.
With the six points 0,0, 1000,0, 0,1000, 1000,1000, 0,2000, 1000,2000 the result is a strip 2000 high, but made of two separate Solid objects, the second spanning heights 1000 to 2000. Each piece is its own object: one click selects one piece, and moving the whole strip means selecting every piece.
Checking a drawing full of fills
Drawings received from others often mix SOLID fills and solid hatches that look identical. To tell which is which, select a fill and read the object name in Properties: Solid or Hatch. If it is a Solid and you need its area, draw a polyline through its corners and hatch that instead.
If a whole drawing suddenly shows outlines only, do not redraw anything. Type FILLMODE and read the value. If it is 0, set it to 1 and REGEN; every fill, SOLID and hatch alike, comes back, because the objects were never changed, only the way they are displayed.
A final tip for symbols: when you build a block such as a level marker or a north arrow with SOLID fills, pick the points in Z order from the start and check the result with FILLMODE at 0. The outline view makes a bow tie obvious in a way the filled view does not, especially when the two halves are small.
Three things often repeated that are not true
| Often repeated | What holds on the 2027 release |
|---|---|
| Picking four corners in turn gives a quadrilateral | Going round gives a bow tie; pick in a Z |
| SOLID and a solid hatch are the same | A SOLID object has no area; a hatch does |
| Missing fills mean a damaged drawing | Usually FILLMODE is 0 |
| Continuing past four points makes one object | Six points gave two separate Solid objects |
Frequently asked questions
What does the solid command in AutoCAD do?
It fills a triangle or quadrilateral from three or four picked points; alias SO.
Why did I get a bow tie?
You picked the corners going round. Pick in a Z: bottom left, bottom right, top left, top right. Type U and redraw in that order.
Why do my fills show as outlines only?
FILLMODE is 0. Set it to 1 and type REGEN; the fills return because the objects were never changed.
How do I fill a circle?
SOLID only fills triangles and quadrilaterals. Use a hatch with the SOLID pattern, selecting the circle as its boundary.
Can I read the area of a solid fill?
With a hatch, yes: a 1000 × 1000 square gives 1 000 000. A SOLID object has no area property.
Should I still use SOLID?
For small three- or four-sided fills it is quick. Otherwise, a solid hatch is the better tool, because it fills any closed shape and reports its area.