# JOIN in AutoCAD

> How AutoCAD's JOIN (J) works: lines and arcs that meet into a polyline, collinear lines into one, arcs into a circle, curves into a spline. Try it free online.

JOIN makes one object of several. Select them, as many as you like, and press Enter: lines and arcs that meet end to end become one polyline, joined to a polyline among them if there is one; lines on one straight line become one line, over any gap; arcs of one circle become one arc, and when they close, JOIN asks whether to make it a circle, `Yes` by default, or keep it as an arc with `No`. Elliptical arcs of one ellipse become one arc, and a spline or an elliptical arc among curves that meet makes a spline. It then says what it made, and how many objects it left out. A polyline joins only by its ends, and a closed one joins nothing. The join is one step that Undo takes back.

- **Command:** `JOIN`
- **Aliases:** `J`
- **Panel:** [Modify](https://mellowcad.com/docs/commands.md#modify)
- **Try it:** [Open the editor](/draw), type `J` and press Enter.

## At the command line

The engine draws it and writes its history as you would type it: the prompts in AutoCAD 2027's order, with the same option letters.

Three lines joined into one polyline, which one pick of OFFSET then follows whole.

```text
Command: JOIN
Select source object or multiple objects to join at once: 1 found
Select objects to join: 1 found, 2 total
Select objects to join: 1 found, 3 total
Select objects to join:
3 objects converted to 1 polyline
Command: OFFSET
Current settings: Erase source=No  Layer=Source  OFFSETGAPTYPE=0
Specify offset distance or [Through/Erase/Layer] <Through>: 8
Select object to offset or [Exit/Undo] <Exit>:
Specify point on side to offset or [Exit/Multiple/Undo] <Exit>:
Select object to offset or [Exit/Undo] <Exit>:
```

## Options

### `cLose` (`L`)

When an elliptical arc is the source, picked alone: makes its ellipse whole.

## What it does not do yet

AutoCAD's own step when a single line, arc or polyline is the source, picked alone (`Select lines to join to source:`): here it joins nothing. A closed object picked alone, which AutoCAD asks again for. Helixes, objects in a tilted plane or upside down, and lines that do not lie in one plane, which AutoCAD joins into a 3D polyline or flattens into a polyline.

[What it does and still lacks, in detail (in English)](https://github.com/ovelilla/mellowcad/blob/main/docs/coverage/modify.md#join--j--es-unir--u--pt-br-unir--une)

## Questions

### What is the shortcut for JOIN in AutoCAD?

`J`, then Enter or Space. The full name works too, and `_JOIN` in any language of AutoCAD.

### How do I join lines into a polyline in AutoCAD?

Run JOIN, select the lines, with a window if you like, and press Enter: those that meet end to end become one polyline.

### Why does JOIN not work?

The objects must meet exactly, end to end and in one plane: a gap or a crossing leaves them out, and JOIN says how many it discarded. Only collinear lines, arcs of one circle and arcs of one ellipse are joined over a gap. A closed polyline joins nothing.

### How do I join arcs into a circle?

Select arcs of one circle that cover it all, and press Enter: JOIN asks whether to convert them to a circle, and `Yes`, the default, does.

## Related commands

- [PEDIT in AutoCAD](https://mellowcad.com/docs/commands/pedit.md)
- [EXPLODE in AutoCAD](https://mellowcad.com/docs/commands/explode.md)
- [BREAK in AutoCAD](https://mellowcad.com/docs/commands/break.md)
- [PLINE in AutoCAD](https://mellowcad.com/docs/commands/pline.md)