How to Enter Dates in SUMIF

1. Open the Microsoft Excel 2010 spreadsheet where you want to create your SUMIF formula.
2. Click on the cell where you want to create your formula. Enter the following into the cell, without quotes: '=SUMIF(A1:A10,'. Change 'A1' to the first cell in the column of dates that you are searching through, and 'A10' to the last cell in that column.
3. Enter the following formula, without quotes, after the comma in your SUMIF formula: 'DATE(2011,x,y),'. Change '2011' to your desired year, 'x' to your desired month and 'y' to your desired day. The DATE function will ensure that your spreadsheet will still work if someone using a different date format opens it.
4. Use a range of dates, instead of a single date, by placing a greater than or less than sign before the date. Since you are using the DATE function, you will need to connect the two commands with an ampersand. For example, to sum all the dates on or before March 30th, 2011, enter the following after the first comma in the SUMIF formula: ''
5. Complete the formula by entering the range of cells that hold the actual values you want to add. Enter this range of cells as follows, without quotes: 'B1:10)'. Change 'B1' to the first cell you want to sum, and 'B10' to the last cell. Press 'Enter' to complete your formula.