# Psscale (colorbar) and its label font size

**URL:** <https://forum.generic-mapping-tools.org/t/psscale-colorbar-and-its-label-font-size/6472>\
**Category:** Q&A\
**Tags:** gmt\
**Created:** [July 22, 2026, 7:09am UTC](https://forum.generic-mapping-tools.org/t/psscale-colorbar-and-its-label-font-size/6472 "2026-07-22T07:09:39Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![yvonnefroehlich](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/yvonnefroehlich/32/5064_2.png) [@yvonnefroehlich](https://forum.generic-mapping-tools.org/u/yvonnefroehlich)\
**Post date:** [July 22, 2026, 9:37am UTC](https://forum.generic-mapping-tools.org/t/psscale-colorbar-and-its-label-font-size/6472/2 "2026-07-22T09:37:43Z")

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Hi @carlosfherrera,

The behaviour you describe is the expected behaviour for GMT \>= 6.5.0.  
Please see similar posts for details:

- GMT forum: [Multiple colorbars changes the annotation fontsize - #13 by JonathonLeonard](https://forum.generic-mapping-tools.org/t/multiple-colorbars-changes-the-annotation-fontsize/4945/13)
- GitHub PyGMT: [Colorbar annotation size does not change · Issue #3041 · GenericMappingTools/pygmt · GitHub](https://github.com/GenericMappingTools/pygmt/issues/3041#issuecomment-3225098860) and following comments
- GitHub GMT: [Fix incorrect font for colorbar unit by PaulWessel · Pull Request #6802 · GenericMappingTools/gmt · GitHub](https://github.com/GenericMappingTools/gmt/pull/6802)

Currently, users need to redo the scaling manually following the scaling factor \sqrt{colorbar\_width/15}, please see the note in the PyGMT documentation at [pygmt.Figure.colorbar — PyGMT](https://www.pygmt.org/v0.19.0/api/generated/pygmt.Figure.colorbar.html#pygmt.Figure.colorbar).

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