# How to change min-max values of colorbar

**URL:** <https://forum.generic-mapping-tools.org/t/how-to-change-min-max-values-of-colorbar/3103>\
**Category:** Q&A\
**Created:** [July 10, 2022, 8:13am UTC](https://forum.generic-mapping-tools.org/t/how-to-change-min-max-values-of-colorbar/3103 "2022-07-10T08:13:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![muhammetnergizci](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/muhammetnergizci/32/2086_2.png) [@muhammetnergizci](https://forum.generic-mapping-tools.org/u/muhammetnergizci)\
**Post date:** [July 10, 2022, 8:13am UTC](https://forum.generic-mapping-tools.org/t/how-to-change-min-max-values-of-colorbar/3103/1 "2022-07-10T08:13:12Z")

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hello everyone, I created a topographic map of Turkey, However, there is sea depth ınformation in the colorbar. I want the color bar to start from zero, not including sea depth. How can I change the starting value of colorbar?

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**Author:** ![seisman](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/seisman/32/4_2.png) [@seisman](https://forum.generic-mapping-tools.org/u/seisman)\
**Post date:** [July 10, 2022, 8:31am UTC](https://forum.generic-mapping-tools.org/t/how-to-change-min-max-values-of-colorbar/3103/2 "2022-07-10T08:31:32Z")

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See if the **-G** option of `colorbar` of what you need

> **[colorbar — GMT 6.4.0 documentation](https://docs.generic-mapping-tools.org/latest/colorbar.html#g)**

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<div class="post-metadata">

**Author:** ![muhammetnergizci](https://yyz1.discourse-cdn.com/flex047/user_avatar/forum.generic-mapping-tools.org/muhammetnergizci/32/2086_2.png) [@muhammetnergizci](https://forum.generic-mapping-tools.org/u/muhammetnergizci)\
**Post date:** [July 10, 2022, 9:19am UTC](https://forum.generic-mapping-tools.org/t/how-to-change-min-max-values-of-colorbar/3103/3 "2022-07-10T09:19:49Z")

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Thank you!!