It looks like the formatting for your table got messed up by the forum software, but I’m going to guess that you come from a spreadsheet background and want to calculate how a value has changed compared to the “previous” row.
Airtable formula fields do not work across rows. This is one way in which an Airtable base is very different from a spreadsheet.
You might be able to approximate what you want by using linked record fields and linking records to their previous/next records. Then you can use lookup/rollup fields to bring the previous/next value into the current record and do calculations from there. However, maintaining all the links has its own headings. There also isn’t enough data to know if it would be possible to calculate the “Usage per day”.
