i3 FAQ - Individual question feed

Set window to fixed (percentage) size

Fri, 01 Feb 2013 08:50:30 +0000

Dear all, Is there a way to change the size of a window to a certain percentage of its parent container? I'd like shortcuts to swap between a window width of 70%/30% and 30%/70% of the parent container. I've only come across the resize grow/shrink commands, but those don't take into account the current size. best regards, Tom

Answer by Michael for
Dear all,

Is there a way to change the size of a window to a certain percentage of its parent container? I'd like shortcuts to swap between a window width of 70%/30% and 30%/70% of the parent container. I've only come across the resize grow/shrink commands, but those don't take into account the current size.

best regards, Tom

Sun, 03 Feb 2013 12:59:17 +0000

As you figured out, there is currently no way to do that (as of i3 v4.4). You can write a simple script which uses the IPC interface (see http://i3wm.org/docs/ipc.html) and then sends the necessary commands based on the current percentages.

Answer by Tom Francart for
Dear all,

Is there a way to change the size of a window to a certain percentage of its parent container? I'd like shortcuts to swap between a window width of 70%/30% and 30%/70% of the parent container. I've only come across the resize grow/shrink commands, but those don't take into account the current size.

best regards, Tom

Wed, 06 Feb 2013 16:01:10 +0000

Thanks for your response, Michael! I wrote the following very simple script (pardon my language, it's my first attempt at python): import i3 import sys targetwidth = float(sys.argv[1]) # get currently focused window current = i3.filter(nodes=[], focused=True) currentsize = current[0]['percent'] * 100; d = int(targetwidth - currentsize) if d>0: i3.resize("grow width" + str(d) + " px or " + str(d) + " ppt"); else: i3.resize("shrink width" + str(-d) + " px or " + str(-d) + " ppt"); While this works nicely, I'm confused by the px and ppt syntax. The manual states the following: resize [ px] [or ppt] ... The optional pixel argument specifies by how many pixels a floating container should be grown or shrunk (the default is 10 pixels). The ppt argument means percentage points and specifies by how many percentage points a tiling container should be grown or shrunk (the default is 10 percentage points). The way I understand this, is that for a tiling container, the px argument will be ignored and vice versa. This however does not seem to be the case. i3-msg resize grow width 5 px Grows my tiling window by what appears to be 5%. i3-msg resize grow width 5 ppt Does not have any effect While if I use i3-msg resize grow width px 5 ppt anynumer seems to be ignored. Perhaps this could be clarified in the user manual?

Comment by Tom Francart for

Thanks for your response, Michael!

I wrote the following very simple script (pardon my language, it's my first attempt at python):

import i3
import sys

targetwidth = float(sys.argv[1])

# get currently focused window
current = i3.filter(nodes=[], focused=True)
currentsize = current[0]['percent'] * 100;

d = int(targetwidth - currentsize)

if d>0:
    i3.resize("grow width" + str(d) + " px or " + str(d) + " ppt");
else:
    i3.resize("shrink width" + str(-d) + " px or " + str(-d) + " ppt");

While this works nicely, I'm confused by the px and ppt syntax. The manual states the following:

resize <grow|shrink> <direction> [<px> px] [or <ppt> ppt]

... The optional pixel argument specifies by how many pixels a floating container should be grown or shrunk (the default is 10 pixels). The ppt argument means percentage points and specifies by how many percentage points a tiling container should be grown or shrunk (the default is 10 percentage points).

The way I understand this, is that for a tiling container, the px argument will be ignored and vice versa. This however does not seem to be the case.

i3-msg resize grow width 5 px

Grows my tiling window by what appears to be 5%.

i3-msg resize grow width 5 ppt

Does not have any effect

While if I use

i3-msg resize grow width <anynumber> px 5 ppt

anynumer seems to be ignored.

Perhaps this could be clarified in the user manual?

Thu, 07 Feb 2013 15:15:09 +0000

Correct me if I'm wrong, but is the explanation in the manual compatible with the fact that "i3-msg resize grow width 5 px" grows a tiling window by 5 ppt?

Comment by Michael for

Thanks for your response, Michael!

I wrote the following very simple script (pardon my language, it's my first attempt at python):

import i3
import sys

targetwidth = float(sys.argv[1])

# get currently focused window
current = i3.filter(nodes=[], focused=True)
currentsize = current[0]['percent'] * 100;

d = int(targetwidth - currentsize)

if d>0:
    i3.resize("grow width" + str(d) + " px or " + str(d) + " ppt");
else:
    i3.resize("shrink width" + str(-d) + " px or " + str(-d) + " ppt");

While this works nicely, I'm confused by the px and ppt syntax. The manual states the following:

resize <grow|shrink> <direction> [<px> px] [or <ppt> ppt]

The way I understand this, is that for a tiling container, the px argument will be ignored and vice versa. This however does not seem to be the case.

i3-msg resize grow width 5 px

Grows my tiling window by what appears to be 5%.

i3-msg resize grow width 5 ppt

Does not have any effect

While if I use

i3-msg resize grow width <anynumber> px 5 ppt

anynumer seems to be ignored.

Perhaps this could be clarified in the user manual?

Sun, 10 Feb 2013 14:51:08 +0000

Well, you are sending a wrong command, so behavior is somewhat undefined (preferably it should error out clearly, though). In case you feel strongly about this, feel free to submit a patch to http://cr.i3wm.org/ or file a bug report at http://bugs.i3wm.org/

Comment by Michael for

Thanks for your response, Michael!

I wrote the following very simple script (pardon my language, it's my first attempt at python):

import i3
import sys

targetwidth = float(sys.argv[1])

# get currently focused window
current = i3.filter(nodes=[], focused=True)
currentsize = current[0]['percent'] * 100;

d = int(targetwidth - currentsize)

if d>0:
    i3.resize("grow width" + str(d) + " px or " + str(d) + " ppt");
else:
    i3.resize("shrink width" + str(-d) + " px or " + str(-d) + " ppt");

While this works nicely, I'm confused by the px and ppt syntax. The manual states the following:

resize <grow|shrink> <direction> [<px> px] [or <ppt> ppt]

The way I understand this, is that for a tiling container, the px argument will be ignored and vice versa. This however does not seem to be the case.

i3-msg resize grow width 5 px

Grows my tiling window by what appears to be 5%.

i3-msg resize grow width 5 ppt

Does not have any effect

While if I use

i3-msg resize grow width <anynumber> px 5 ppt

anynumer seems to be ignored.

Perhaps this could be clarified in the user manual?

Thu, 07 Feb 2013 15:06:44 +0000

The syntax of the resize command already is clarified in the git version: http://build.i3wm.org/docs/userguide.html#resizingconfig

Answer by ticcky for
Dear all,

Is there a way to change the size of a window to a certain percentage of its parent container? I'd like shortcuts to swap between a window width of 70%/30% and 30%/70% of the parent container. I've only come across the resize grow/shrink commands, but those don't take into account the current size.

best regards, Tom

Tue, 30 Sep 2014 09:31:53 +0000

Here's my workaround for floating windows to resize window to 400x800px: for_window [title="Tasks.*"] floating enable; resize shrink width 10000px; resize grow width 400px; resize shrink height 10000px; resize grow height 800px;