If your Excel worksheet contains calculations that are based on a changing range of cells, use the SUM and OFFSET functions together in a SUM OFFSET formula to simplify the task of keeping the calculations up to date.
How to use the Excel SUM and OFFSET functions
If you are using calculations over a period that is constantly changing, such as determining sales figures for the month, you can use the OFFSET function in Excel to set a dynamic range that changes as each day's sales figures are added.
By itself, the SUM function can usually handle the insertion of new cells containing data into the range being summed. One exception occurs when the data is inserted into the cell where the function currently resides.
In the example below, new sales figures for each day are added to the bottom of the list. This causes the total to shift down one cell each time new data is added.