Comparing build sizes - jonas-rem/RIOT GitHub Wiki
There is a make target for build size comparison. You can use it like that:
$ cd RIOT/test/test_something
$ git checkout master
$ make buildtest BINDIRBASE=master-bin
$ git checkout my-branch
$ make buildtest BINDIRBASE=my-branch-bin
$ make info-buildsizes-diff OLDBIN=master-bin NEWBIN=my-branch-bin
text data bss dec BOARD/BINDIRBASE
0 0 0 0 avsextrem **← this line contains the diff**
57356 1532 96769 155657 master-bin
57356 1532 96769 155657 my-branch-bin
...
Note: make info-buildsizes-diff needs bash 4, so your system must not be older than 20-Feb-2009 …
Check it out, the output contains colors. ;)
(This page is mostly a copy of René Kijewski's explanation in https://github.com/RIOT-OS/RIOT/pull/1033.)