I have create a shape in inkscape and now want to finish it by creating a smooth arc between the last 2 end points.


Edit In response to step 9, union splits the shape not joins it. It seems to create a union of the arcs not join the shape.

Select all

Select all lines and arcs

Path -> Union

union split shape

  • Are you working with a stroke (i.e. a line) here, rather than a filled object?
    – z3z
    Commented Apr 11, 2017 at 23:37
  • Yes i created a straight line then an arc and joined the arc to the line and then another straight line.
    – sayth
    Commented Apr 12, 2017 at 0:00
  • 1
    This is a shape which could be easily drawn in one go, as a closed path, with the Bézier Tool. If you want to find a tutorial on how to use it, you can find one by searching google for "bezier tool inkscape tutorial".
    – Billy Kerr
    Commented Apr 12, 2017 at 8:45

1 Answer 1


Give this a try...

Select the Bezier tool (Shift + F6) then look for the Bezier Mode on the taskbar, and select spiro path.

It'll probably be easier if you turn on Snapping and enable "Snap cusp nodes incl. rectangle corners"

With the bezier tool, snap onto the top edge of your shape. Then click a couple more times before snapping onto the bottom edge. After clicking at the bottom, hit return. You should have a line that looks something like what is shown in the pic below.

Press F2 to get the node tool and click the black line once. This will display the nodes on the line. Drag the mouse over the two nodes in the middle to highlight them. Note, do NOT highlight the end nodes!

Now, on the main taskbar, click the button that says "Make selected nodes smooth" and this will start to imitate a smooth curve. Move the nodes around slightly if the angle looks slightly off or not quite smooth.

Finally, drag the mouse over both lines to select, then on the Path menu, click Union. This will unify your two lines into one object.

Here's a pic showing the instructions in greater detail.

Smooth curve in Inkscape

  • All works except union which creates a line as union for the arc. Will add image to question
    – sayth
    Commented Apr 12, 2017 at 1:39
  • Convert the arc in your original shape to a path, if you haven't done that already. Does that make a difference? Also try unifying a couple of lines at a time instead of the whole thing. When i tried it, I had your original shape as one object and union worked just fine.
    – z3z
    Commented Apr 12, 2017 at 6:15

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