# Calculate difference between numbers in 2 columns row-by-row in a spreadsheet

I have 3 columns in a Google Docs spreadsheet: A) Inventory purchased price, B) Inventory sold price, C) Difference between A and B (i.e. profit or loss)

Data is going to be entered manually into columns A and B. How do I make column C to 1) display the calculated amount for each row, and 2) color profitable sales in green and unprofitable in red?

• For 2, you want "conditional formatting". There are already several questions here on that topic; just do a search.
– ale
Commented Apr 11, 2015 at 11:21

## 1 Answer

.. and for the first question, assuming your data start in row 2, in C2 try:

``````=ArrayFormula(if(len(A2:A)*len(B2:B), B2:B-A2:A,))
``````

This formula should automaticcaly output the difference between B and A when data is entered. See if that works ?

• It worked fantastically. Thank you very much! Commented Apr 11, 2015 at 16:38
• How would I do it if all numbers are in one single column and I want to calculate the difference between the current row and the row above? Like =A2-A1 and make this continue down "forever". Commented May 19, 2020 at 15:16