Panel for Nuke that allows you to quickly estimate size of all sources in the script.
Also can be used as imported module to provide same functionality for another tool.

1. cd ~/.nuke && git clone https://github.com/artaman/estimator.git
2. Open ~/.nuke/init.py with your favourite editor
3. Add the following code:

#
# Estimator
#
import os, nuke
estimator_path = os.getenv("HOME") + "/.nuke/estimator"
if os.path.exists(estimator_path):
    nuke.pluginAddPath(estimator_path)
    print "~ Adding Estimator panel..."
    import estimator
else:
    print "! Estimator path can't be found, going on..."

After following steps above you will have a new panel called "Estimator". By default it is dockable, but can be dragged out and used as a modal window:

• Frames to calculate — Amount per read node. Default should be just fine for most cases, increase if you want more precision.
• Show full path — Self-descriptive.
• Estimate disabled nodes – Self-descriptive, on by default.
• Sort by size – Wait until calculation is done and display results sorted.

Click 'Run' and enjoy the fact you can use Nuke while script is doing its job in separate thread.

estimator_path = os.getenv("HOME") + "/.nuke/estimator"
sys.path.append(estimator_path)
from estimator_panel import estimatorPanel

calc = estimatorPanel()
reads = calc.evaluate_script(2)

print reads
# {'/path/to/sequence_%0Xd.xxx': [first_frame, last_frame, size_in_bytes]}

.