Until last week I was thinking that increasing the taskbar thumbnail window size is not possible natively in Windows 7 (and Windows Vista). Well! Windows 7 supports the ability to increase the thumbnail preview size natively, through registry edits which I’m covering in this article.

This is how the taskbar thumbnail preview window appeared prior to applying the following edit.

Make the Taskbar Thumbnail Preview Bigger in Windows 7

1. Launch Regedit.exe and navigate to the following location:

HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ Taskband

2. Create a DWORD value named MinThumbSizePx

3. Double-click MinThumbSizePx and set its value data accordingly. I set it to 350 (Decimal) for this example.

4. Exit the Registry Editor.

5. Logoff and login back.

And you can see below that the taskbar thumbnails has grown bigger in size.

Additional Information

Similarly, you can tweak the following registry values under the "Taskband" registry branch, and customize the taskbar thumbnail previews as you need. Here is the entire list:

  1. NumThumbnails
  2. MinThumbSizePx
  3. MaxThumbSizePx
  4. TextHeightPx
  5. TopMarginPx
  6. LeftMarginPx
  7. RightMarginPx
  8. BottomMarginPx
  9. ThumbSpacingXPx
  10. ThumbSpacingYPx

Editor’s Note: Hoping to write an program to customize Windows 7 Taskbar Thumbnails based on the above registry edit. In Windows Vista, the feature was made available by a nice little program called Vista Thumbnail Sizer by Andreas Verhoeven, which was announced by the How-To Geek Website.

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  1. said this on Wednesday, July 24th 2013 5:25 pm

    My guess is that TextHeightPx is height of the text used for each thumbnail, in pixels – so not the same as font size but measuring a similar thing.

    Guesses again but from (to me more obvious, as a developer) names:
    NumThumbnails is probably a max/min setting or how many wide the row of thumbnails is.
    ThumbSpacingYPx is likely to be the size of the padding space above/below each thumbnail (the ‘Y’ likely to mean vertical direction, as in y-axis of a graph or the y of x,y coordinate systems)
    ThumbSpacingXPx will be similar but between each thumbnail horizontally (‘X’ as in x-axis of a graph)

  2. said this on Wednesday, April 7th 2010 5:31 pm

    [...] If you’d prefer to change the settings manually without using a dedicated application, here’s a list of the registry changes you can make to accomplish this by [...]

  3. jefe
    said this on Friday, March 26th 2010 5:12 pm

    will that ever be possible for the thumbsize of the previews in alt+tab ???

  4. Abdullah
    said this on Tuesday, March 9th 2010 7:17 pm

    @Ramesh Srinivasan : it worked , thanks a lot !

  5. shadeMe
    said this on Tuesday, March 9th 2010 7:50 am

    Someone finally figured it out – Great work! I was considering writing a shell hook to do the same (like Ave’s tool for Vista), thinking there weren’t any registry keys that would let me do it.

    Once again, brilliant work!

  6. anon
    said this on Monday, March 8th 2010 7:38 pm

    Well some of the values are obvious, like Left, Right, Bottom or TopMarginPx and Thumb Spacing but wht about TextHeightPx?

  7. anon
    said this on Monday, March 8th 2010 7:28 pm

    Merely restarting Explorer is enough, logoff isn’t necessary. I knew about the Vista trick but didn’t know about the Windows 7 since the registry keys and values are totally different? How do you discover these reg values? Registry monitoring? Can you explain what the other registry values are for?

  8. Abdullah
    said this on Sunday, March 7th 2010 7:06 pm

    what about vista ? is there anyway to enlarge the thumbnails ?

  9. anonymouse
    said this on Sunday, March 7th 2010 3:04 pm

    Can you give more details on the following options:

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