I read through the docs of chemfig, but it seems like there is no option to control the size of an arrowhead (except you define an arrow from scratch, what I can't do yet). The closest thing I have found ist


\schemestart A\arrow{<=>[up][down]}[-90,1.2,,thick]B \schemestop

to control the thickness and thus the size of the head, but of of course it's not purely what I want.

In my case I want to separately adjust the arrowhead.

Also it would be preferable to draw two filled heads and not the harpoon-like ones.


  • 1
    What do you mean by "size"? Length, width, type ... ? // Please, don't use class minimal: it's not intended for use. use e.g. this one instead: \documentclass[10pt,border=3mm,tikz]{standalone}
    – MS-SPO
    Commented Jul 10 at 12:36
  • 1
    Alright, you answered the question already perfectly. Now I can adjust the size/scale of my arrowhead easily.
    – Leon
    Commented Jul 10 at 16:39

1 Answer 1


Here's one way to do it:

  • use \setchemfig to change the arrow head
  • use tikzlibrary arrows.meta (see ch. 16.5 in the pgfmanual)
  • choose one of those heads and set its parameters

For demonstration purposes I selected a Barb tip. Kindly notice the surrounding {} to match up with chemfig-syntax. The , at the end doesn't hurt, and you won't forget it if you'd extend the list.

After all, chemfig is based on TikZ, though it's not always easy to see. In reverse, using things that would work with plain-TikZ (i.e. non-chemfig) almost always is a good starting point.

\setchemfig{arrow head=-{Arc Barb[width=10pt,length=8pt]},}




 \setchemfig{arrow head=-{Arc Barb[width=10pt,length=8pt]},}


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