# Choosing Compression

**URL:** <https://kopia.discourse.group/t/choosing-compression/8909>\
**Category:** Support\
**Created:** [May 22, 2026, 4:36am UTC](https://kopia.discourse.group/t/choosing-compression/8909 "2026-05-22T04:36:51Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![uew93h](https://avatars.discourse-cdn.com/v4/letter/u/5e9695/32.png) [@uew93h](https://kopia.discourse.group/u/uew93h)\
**Post date:** [May 22, 2026, 4:36am UTC](https://kopia.discourse.group/t/choosing-compression/8909/1 "2026-05-22T04:36:51Z")

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When to choose what ?

By default none is selected

 ![image](https://global.discourse-cdn.com/free1/uploads/kopia/original/2X/b/bd5df66d442a2551482e30dd7f88f4bb598a210b.png)

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**Author:** ![budy](https://yyz2.discourse-cdn.com/free1/user_avatar/kopia.discourse.group/budy/32/38_2.png) [@budy](https://kopia.discourse.group/u/budy)\
**Post date:** [May 22, 2026, 1:26pm UTC](https://kopia.discourse.group/t/choosing-compression/8909/2 "2026-05-22T13:26:56Z")

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Depends on your hardware - usually zstd strikes the best balance between compression and performance.

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**Author:** ![uew93h](https://avatars.discourse-cdn.com/v4/letter/u/5e9695/32.png) [@uew93h](https://kopia.discourse.group/u/uew93h)\
**Post date:** [May 22, 2026, 5:39pm UTC](https://kopia.discourse.group/t/choosing-compression/8909/3 "2026-05-22T17:39:50Z")

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it takes 8-12 hours one first backup and 20-30minutes for snapshot with no changes, how much time will zstd add ?

I currently use no compress ie default can I switch to zstd ? Also can I switch back to no compression ?

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**Author:** ![budy](https://yyz2.discourse-cdn.com/free1/user_avatar/kopia.discourse.group/budy/32/38_2.png) [@budy](https://kopia.discourse.group/u/budy)\
**Post date:** [May 22, 2026, 9:26pm UTC](https://kopia.discourse.group/t/choosing-compression/8909/4 "2026-05-22T21:26:57Z")

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zstd causes veeery little overhead, but will only work on not yet compressed files. So mostly text files, as most of the graphics and video formats already perform compression internally. On average I am seeing a 10 to 15% space reduction on mixed data volumes, but… it almost cost nothing, so why not?

You always enable compression, but that setting will not re-write the data in your repo - the compression will only be applied to newly written data.