AutoSum is the one button that turns Excel from a place to type numbers into a thing that does the maths for you. By the end of this page you will be able to total a column of figures in two clicks, and you will understand what Excel quietly wrote on your behalf.
Say you have a list of numbers running down a column — expenses, patient counts, hours worked. You want the total at the bottom. You could add them up on a calculator and type the answer in, but then the answer is frozen: change one number and the total is quietly wrong. AutoSum solves that.
- The cell shows the answer, 60
- The formula bar shows the real instruction
- Confirms A4 is the selected cell
The button lives on the Home tab, over on the right-hand side, and looks like the Greek letter sigma: Σ. It is also on the Formulas tab. Both are the same button, so use whichever you find first.
Try it yourself
In cell A1 type 10, press Enter, type 20, press Enter, type 30, press Enter.
You now have three numbers in A1, A2 and A3, and your cursor is sitting in A4 — the empty box directly beneath the list.
With A4 still selected, click AutoSum (Σ) on the Home tab.
Excel looks upward from the selected cell, finds the run of numbers, and proposes to add exactly those. You will see a dashed moving border around A1 to A3.
Look at what appeared in A4, then press Enter to accept it.
A4 shows =SUM(A1:A3) before you press Enter, and 60 afterwards. Pressing Enter is you saying "yes, that is the range I meant".
Click back on A2, type 25 and press Enter.
The total changes to 65 on its own. This is the whole point: you maintain the numbers, Excel maintains the answer.
Click on A4 once and look at the formula bar along the top.
The cell shows the answer, but the formula bar shows the instruction behind it. That difference trips up everyone at first.
Because the range is just an address, you can widen it by hand. Click the cell, click into the formula bar, change A3 to A9, and press Enter — Excel now adds nine boxes instead of three, empty ones included, which is handy when you know your list is going to grow.
Words people use
Check yourself
If you can say yes to each of these, you are ready for the next lesson.
- I can find the AutoSum button on the Home tab
- I can total a column of numbers without typing the answer myself
- I can read =SUM(A1:A3) and say what it means
- I know the difference between what a cell shows and what the formula bar shows