AutoSum Doesn’t Always Predict My Data Correctly

January 04, 2022 - by Bill Jelen

AutoSum Doesn’t Always Predict My Data Correctly

Problem: When I use the AutoSum button, Excel sometimes predicts the wrong range of data to total. Below, AutoSum worked fine in F2 and F3, but in cell F4, Excel thought I wanted to total the rows above F4. How do I enter the correct range?

Strategy: After you press the AutoSum button, the provisional range address is highlighted in the provisional formula. Using your mouse, you highlight the correct range.

Adding the Total column is a little buggy. It works fine in F2 and F3, but if you would do it in F4, Excel wants to add the two numbers above you. Before accepting the formula, you have to select B4:E4 with the mouse.
Figure 249. Excel chose the column instead of the row

AutoSum will work correctly in F2 and F3. It will predict that you want to sum the data in that row. However, in cell F4, Excel has a choice: either sum the two cells in that column or the four cells in the row. Excel always chooses to sum the two cells above in this situation.

After you press the AutoSum button, note that F2:F3 is highlighted in the formula. This allows you to enter the correct range. There are three methods:

  • With the mouse, highlight B4:E4 and press Enter.
  • With the keyboard, type B4:E4.
  • Using the arrow keys, press the Left Arrow key to move to E4. While holding down the Shift key, press the Left Arrow key three times to highlight B4:E4.

AutoSum can also fail when one number in your range contains a SUM formula. The provisional formula will offer to sum a formula extending up to but not including the previous SUM formula.

Alternate Strategy: You can choose to enter all the totals at one time by using the AutoSum button. This is faster than the methods just described and will eliminate the problem described. Follow these steps:

  • 1. Highlight the entire range that needs a SUM formula.

Half of the cool technique: Select all of the blank cells in the Total column F2:F10 before clicking the AutoSum.
Figure 250. Select the entire range
  • 2. Press the AutoSum button. Excel makes a prediction and fills in the total formulas automatically. Excel does not show the provisional formula, so check one formula to see that it is correct.

One press of the AutoSum fills in all 9 formulas for the Total Column.
Figure 251. Provisional formulas are not displayed.

Gotcha: Headings that contain dates or numeric years can really cause problems for AutoSum. Excel will usually get fooled into including the heading in the sum. Be extra cautious when using AutoSum in these situations. Here, Excel incorrectly included the headings in row 1.

A problem with numeric headings. Instead of month names in B1:E1, there are now year numbers. If you select B10:E10 and hit AutoSum, you may not realize that Excel included the Year number in the Sum.
Figure 252. The numeric year headings are mistakenly included.

There is an amazing workaround. You can select the cells to be totaled plus one extra row and one extra column.

Finally, the cool trick. Before adding any sums, select B2:F10. This is all of the numbers, plus the empty total row and the empty total column.
Figure 253. Select an extra row and an extra column

When you click the AutoSum button, Excel correctly adds SUM formulas in the total row and total column.

Press AutoSum once and all of the totals are filled in all the way around.
Figure 254. Add totals in one click.

Another AutoSum oddity is shown here. The cellpointer is directly below a SUM function. There are additional SUM functions in the range that would normally be included in the AutoSum. In that case, AutoSum will only include the other SUM functions.

Another oddity showing what the AutoSum can do. This time, there are numbers and SUM functions mixed in to B1:B11. From the blank cell B12, press AutoSum. The formula skips the constants and only picks up the three cells that contain SUM functions. The resulting formula is =SUM(B11,B6,B3).
Figure 255. AutoSum only sums the SUM formulas.

This article is an excerpt from Power Excel With MrExcel

Title photo by Shreyas shah on Unsplash

Bill Jelen is the author / co-author of:
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