I need a way to resize any window (not just Firefox!) to specific sizes.

I need to check what the application I'm writing looks like at these resolutions - how many columns are visible in grids, that sort of thing.

I know I could just change my resolution, but that's a hassle, especially for 800x600 - desktop icons get smooshed together and stuff.

  • 2
    Still, changing the screen resolution also takes the taskbar into account. So, when only resizing application windows, then be sure to make it a bit smaller to account for the available screen estate. – Arjan Feb 9 '11 at 11:37
  • @Arjan: for Chrome, several web extensions offer a way to exactly set the viewport. See f.ex. stackoverflow.com/questions/46998025/… (by me) – serv-inc Oct 29 '17 at 14:16
  • @serv-inc, while true, that's not what this question is about. – Arjan Oct 29 '17 at 14:50
  • VTR as this is easily phrased as a how do I achieve X, not necessarily a give me a program to X – bertieb Feb 14 '18 at 23:21

Check out Sizer ...

Sizer is a tiny freeware utility that gives you an easy and fast way to resize any window to an exact size. It could be a very useful tool for webmasters and web designers.

  • Excellent! That's a very slick program. I hope it eventually supports vista/win7 but for now I'm still on XP anyway. Thanks :) – Blorgbeard Aug 4 '09 at 22:16
  • I have it running under Vista on my main dev box at work without issue. – David Spillett Aug 4 '09 at 22:38
  • @David Spillett: Curious - are you running Vista x86 or x64? – Chris W. Rea Aug 4 '09 at 23:41
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    Problem is there is no version for Windows 7 - 64 Bit :( i've used Sizer for years and now I can't. – user66766 Feb 9 '11 at 11:29
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    The 64bit version is currently under development, but available for download. Works on my machine(tm) – CGK Dec 13 '11 at 22:46

You could write your own with AutoHotkey:

#=:: ; [Win]+[=]
    WinGet, window, ID, A
    InputBox, width, Resize, Width:, , 140, 130
    InputBox, height, Resize, Height:, , 140, 130
    WinMove, ahk_id %window%, , , , width, height


Before: 640 x 480


  1. Press Win+=.

  2. Enter a width:


  3. Enter a height:


After: 400 x 300


Note: To set a length to 0, you have to input 0. An empty value is ignored. For example, if you only want to resize the height, leave the width blank and enter a value for the height.

For the curious: 0 x 0


As you can see, a window with a title bar and controls has an absolute minimum size.

  • For those interested, Here is a similar approach to change one of the four (X,Y,width,height) of active window. autohotkey: how to resize window by both absolute and relative height – qeatzy Oct 18 '17 at 11:30
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    I set a window in W10 to 960x540, but the result is 946x533. Do I need to add a value for the title bar and scrolling bar, so its more an inner dimension than an outer? – mgutt Jun 28 '20 at 9:41
  • @mgutt Same for me. I've found that it can be worked around on a per-application basis with code such as the following just before the line WinMove: if WinActive("ahk_exe chrome.exe") { width += 16 height += 8 } – mythofechelon Sep 20 '20 at 15:00

I suggest WinSize2.

  • Simple, fast, and easy to manage by using Alt++ And Alt+- keys to increase/decrease the size of the current window.
  • Working on any Windows version, or at least I have tested it on Windows XP, 7 and 8.
  • Free Software.

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