Calculates the size of each commit in the current branch

git_commit_sizes.sh

#!/usr/bin/env bash -e

for commit in $(git log --format="%H"); do
  size=0
  blobs=0
  IFS=$'\n'
  for line in $(git log -1 --raw --no-merges --no-renames --no-abbrev --full-index --raw --pretty=oneline $commit | tail -n +2); do
    id=$(echo $line | cut -d' ' -f4)
    blob_size=$(git cat-file -s $id 2>/dev/null || echo 0)
    (( size += blob_size ))
    (( blobs += 1 ))
  done
  echo $commit $blobs $size
done

The output format is:

<commit-sha> <blob count> <commit size>