This calculator gives you an idea about post operative ACD or ELP by predicting it based on preoperatve ACD with optional lens thickness. The utility of this tool is that, incase of post operative surprise you can do a pseudophakic biometry/measurement and check how the lens position match with the predicted post operative ACD.
You can follow the article Refractive Surprise Post IOL Implantation- How to check what went wrong (https://www.quickguide.org/post/refractive-surprise ) on the subject.
This calculator is suggestive and indicative only.