# Large Thumbnails size in the files app **URL:** \ **Category:** ℹ️ Support\ **Created:** [May 5, 2020, 12:37pm UTC](https://help.nextcloud.com/t/large-thumbnails-size-in-the-files-app/80525 "2020-05-05T12:37:08Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![gas85](https://help.nextcloud.com/user_avatar/help.nextcloud.com/gas85/32/7772_2.png) [@gas85](https://help.nextcloud.com/u/gas85)\ **Post date:** [May 5, 2020, 1:35pm UTC](https://help.nextcloud.com/t/large-thumbnails-size-in-the-files-app/80525/2 "2020-05-05T13:35:43Z")
You can generate smaller previews to safe time and bandwidth. Here I wrote small script to use in cron job [How to know if Preview Generator is working? - #6 by gas85](https://help.nextcloud.com/t/how-to-know-if-preview-generator-is-working/41072/6). And then: > [@Previews / data size](https://help.nextcloud.com/t/previews-data-size/46990/2): > > Fist of all you have to adjust what kind of previews you would like to have. I have had the same problem and have to setup my config.php as following to have only FullHD previews maximal (default is 4096): > [@Fairly new with nextcloud but preview folder has huge size](https://help.nextcloud.com/t/fairly-new-with-nextcloud-but-preview-folder-has-huge-size/64390/3): > > And remember, after you change the config, you have to regenerate previews again. Here is a good explanation how: After that you will have nice small previews: ![grafik](https://help.nextcloud.com/uploads/default/original/3X/a/c/ac32edda8eeca57bb3acd7e620da9c4633c70af1.png) But somehow you are right, I checked and there are still previews around 1 and 2 MB (not all of them), that is strange… Seems that some previews were not pregenerated, then access to the file generates new file, but in png instead of jpg and it is quite big: ```auto # du -ah preview/ | grep -E "png|jpg" | sort -h -r | head -n 20 2.9M preview/806331/1536-1024-max.png 2.8M preview/2823/1528-1044-max.png 2.7M preview/2899/1527-1080-max.png 2.5M preview/944452/1920-1080-max.png 2.4M preview/2506474/1920-1080-max.png 2.4M preview/1593491/1620-1080-max.png 2.3M preview/333955/1660-1080-max.png 2.3M preview/2503143/1190-893-max.png 2.1M preview/1593493/1620-1080-max.png 2.0M preview/2952315/1920-1080-max.png 2.0M preview/2503144/1190-893-max.png 1.9M preview/2790359/810-1080-max.png 1.9M preview/1593492/1557-1080-max.png 1.8M preview/2503151/1920-825-max.png 1.7M preview/944586/1500-1000-max.png 1.7M preview/942970/1500-1000-max.png 1.7M preview/802162/1536-1024-max.png 1.7M preview/330791/1500-1000-max.png 1.7M preview/2503150/1190-893-max.png 1.7M preview/1593629/1854-1080-max.png ``` and pre generated previews are in JPG, they are pretty ok: ```auto # du -ah preview/ | grep "jpg" | sort -h -r | head -n 20 552K preview/4588842/1919-1080-max.jpg 544K preview/4587449/1734-1080-max.jpg 536K preview/4588844/1919-1080-max.jpg 528K preview/4588738/1919-1080-max.jpg 516K preview/782965/1920-1080-max.jpg 512K preview/72740/1920-1080-max.jpg 512K preview/6190/1920-1080-max.jpg 512K preview/4588762/1919-1080-max.jpg 512K preview/4588693/1919-1080-max.jpg 500K preview/4588735/1919-1080-max.jpg 500K preview/2788724/1440-1080-max.jpg 500K preview/1057309/1920-1080-max.jpg 496K preview/4588731/1919-1080-max.jpg 496K preview/4535176/1919-1080-max.jpg 496K preview/2788709/1440-1080-max.jpg 488K preview/12135/1920-1080-max.jpg 484K preview/4588843/1919-1080-max.jpg 484K preview/4586368/1919-1080-max.jpg 484K preview/2782961/1440-1080-max.jpg 480K preview/77330/1920-1080-max.jpg ``` --- _[View the full topic](https://help.nextcloud.com/t/large-thumbnails-size-in-the-files-app/80525)._