What does it do?
The Excel SUM function adds up numbers together from a range, this can be a group of cells, individual cells or numbers entered directly into the function. Numbers can be whole, fractions, time, dates, percentages and anything else stored as a number value directly into the cell. It can also sum values that have been created by other formulas.
Syntax Explained
Number1: This is the first number or range to add.
Number2 and up to Number255 (optional): This is any additional numbers or ranges to add.
Examples
1. SUM using numbers inside parenthesis.
Above you can see the numbers entered into the function, here it is adding 1 + 1 +1 to equal 3, we don’t really need a calculator for that, but it serves as a basic example to give you an idea of what it can do. This is very similar to the entering =1+1+1 in the same cell, it will yield the same result.
2. SUM using cell references.
A developed version of example 1, try replicating the above and then change one of the numbers in the Data column to see it update in real time.
Pro Tip
You don’t have to type in the cell ranges B3,B4,B5, you may if you wish, but try click cell B3, then adding a comma, then click B4, then B5. Alternatively, you can hold the left Ctrl key before you start clicking cells. This is useful for adding cells which are scattered and you want to be sure you are referencing the correct data.
3. SUM referencing a range of cells in one column.
A further developed version of example 2 is shown above, this is much quicker to complete the formula since you can select the range of cells with the mouse.
4. SUM referencing a range of cells over two adjacent columns.
This also works over more than one column too, see example 3 slightly tweaked into the above.
5. SUM referencing a range of cells over two non-adjacent columns.
The example above demonstrates how to use the SUM function over multiple rows when they are separated by any number of columns. This is much like a version of the example in point 2. Notice here how the cell ranges in the formula bar are separated by a comma.