Sharing my solution here because I had the same question.
To subtract the value of another row within the same table from the current row in Airtable, you need to:
1) Create a “Link to another Record” column in your table.
- You’ll use this column to link to the record that has the data you need to perform your calculation with, in this case, the previous row. You could title this column “Previous Row.”
2) Create a “Lookup” column in your table.
- Select the column in your table that has the data you need to perform your calculation from the linked record in “Previous Row”.
- So, if the original column that has the data you need in your table is titled “Value”, you could title the new Lookup column “Previous Row Value.”
3) Create a “Formula” column that calculates what you need it to
- In this case, we’re calculating the difference between the current row and the selected row, so the formula would be: Value-{Previous Row Value}
The problem with this solution is that it’s a bit tedious in that you have to manually search for and add the record that has the data you need to complete your calculation, whereas in Excel or similar, you’d just create the formula once and then drag it down the column to the cells that you need to display the calculated result. Perhaps there is a formula that would automatically find and add the previous row, but I’ll let someone else figure that part out…
