How to Keep a Running Average in Excel Automatically

To keep a running average in Excel, enter each observation in column B and put =AVERAGE($B$2:B2) in C2, assuming your first value is in B2; then fill the formula down. Each row will show the average of all numeric values from the first observation through that row. You will need a worksheet with your values in one column and an empty column for the results.

What You’ll Need

Microsoft Excel for Microsoft 365 on Windows. The steps also work in recent desktop versions of Excel.
A column of numeric observations, such as daily sales, temperatures, or test scores. Put the first value below a header so the formula can refer to a clear starting cell.
An empty column beside the observations for the running averages. Dates or labels can go in another column if they help you identify each row.

A running average is a cumulative average: each result includes the current value and all earlier numeric values in the list. It is useful for seeing how an average changes as new measurements arrive. It is different from a moving average, which averages only a set number of recent observations, such as the last seven days.

Step-by-Step

Set up the columns. In a blank worksheet, enter Date in A1, Value in B1, and Running average in C1. If dates are not relevant, you can leave column A out. Enter one numeric observation per row in column B, starting at B2. For example, put 8 in B2, 10 in B3, and 12 in B4. Keep the values in chronological or otherwise meaningful order, because each row’s result includes only the values above it and in that row.
Choose where the first result will go. Click C2, beside the first observation. The result column must start on the same row as the first value. If your data starts on a different row or in a different column, adjust the cell references in the next step to match your layout.
Enter the running-average formula. With the observations in B2 downward and the first result in C2, type =AVERAGE($B$2:B2) in C2 and press Enter. The dollar signs lock the starting cell B2, while the second reference, B2, is relative and advances as the formula is filled down. AVERAGE calculates the mean of the range from the first value through the current row.
Check the first result. With 8 in B2, C2 should show 8, because the average of the single first observation is 8. If the cell displays the formula as text instead of a number, see Troubleshooting below. You can set the display to a suitable number of decimal places without changing the underlying calculation.
Fill the formula down the column. Select C2 and point to the small square at the lower-right corner of the selection, called the fill handle. Drag it down alongside your data. Alternatively, select the formula cell and the cells below it that need results, then use Home > Fill > Down. On Windows, Ctrl+D fills down; in Excel for Mac, use Command+D. The fill handle works across desktop platforms.
Verify the next results with a small example. With 8, 10, and 12 in B2:B4 and the formula filled through C4, the results should be 8, 9, and 10. The second result is (8 + 10) divided by 2, or 9. The third is (8 + 10 + 12) divided by 3, or 10. If your results do not match, check that each formula starts at B2 and ends on the same row as its result.
Format the results for reading. Select the running-average cells and use Home > Number to choose a number format or adjust decimal places. For example, two decimal places might be helpful for measurements such as 10.33. Formatting changes what you see, not the precision used in later calculations; Excel retains the stored values.
Update the average when you add observations. Enter the next value in the next blank row in column B, then copy the formula from the previous row in column C down one row. Excel will extend the ending reference to include the new observation. If your list grows frequently, convert the range to an Excel table with Insert > Table, and include the headers. Excel often carries a calculated-column formula into new table rows; check the new result, and copy the formula down if it does not appear automatically.

For a different starting position, preserve the same pattern: lock the cell containing the first observation and leave the endpoint relative. For instance, if the first value is in D5, the first result belongs beside it on row 5 and the starting reference should point to D5. Do not lock both ends of the range, or every row may keep calculating the same first observation rather than expanding the range.

Common Mistakes

Using the wrong starting cell: If your data begins in B2 but the formula starts at B1, the header may be included in the range. AVERAGE ignores text headers, but the reference is still incorrect and can cause confusion if the layout changes. Start with the cell containing the first numeric observation.

Locking the ending reference: The first reference should remain fixed, but the endpoint needs to change row by row. If both references are absolute, every result can repeat the same average. Check that the starting reference has dollar signs and that the ending row reference does not.

Confusing a running average with a moving average: A running average includes every earlier numeric observation. It does not discard older values after a set number of rows. If you want an average of only the latest seven observations, you need a moving-average calculation instead.

Assuming blank cells and zeros mean the same thing: AVERAGE ignores empty cells and text, but includes a numeric zero. A zero can therefore lower the result, while an empty cell does not add a value to the average. Enter zero only when zero is a real observation.

Sorting only one column: Sorting the values without their matching dates or labels can disconnect each value from its record. Select the full data range before sorting, or use the sort controls on a table, so each row stays together.

Tips

Use clear headers and consistent units. Mixing dollars with cents, or Celsius with Fahrenheit, makes the resulting average misleading even if the formula is correct. If a value is a measurement, keep its unit consistent throughout the source column and label the header accordingly.

Keep the raw observations intact and put calculations in a separate column. That makes it easier to audit the inputs, spot an accidental entry, and reuse the original data for another analysis. If you need to share the results, include the observation date or sequence number beside each running average so readers can see when the average changed.

Do not round the source values just to make the displayed results look tidy. Use number formatting to control visible decimal places instead. Rounding the inputs can change later averages, while formatting usually leaves the stored values untouched.

If you want the newest observation at the top, remember that the ordinary formula described here assumes the list builds downward from its first observation. For a dependable running calculation, keep the observation order consistent and add new rows at the bottom. If you reorder the records, the running values will recalculate according to the new order.

When you expect to add many rows, an Excel table can make the data easier to filter and maintain. Create it by selecting the data, including its headers, and choosing Insert > Table. Tables can extend when you type directly below them, but review the formula in the new row after adding data; workbook settings or edits can affect whether Excel fills it automatically.

Troubleshooting

The cell shows the formula instead of a number. The cell may be formatted as Text, or the formula may have been entered with an apostrophe before the equals sign. Change the cell format to General using Home > Number, then edit the cell and press Enter. Also check that there is no leading apostrophe or space before the equals sign.

The result is #DIV/0!. AVERAGE returns this error when its referenced range contains no numeric values. Confirm that the source cells really contain numbers rather than text that looks like a number, and that the formula points to the intended range. Re-enter a value if it was pasted in as text; changing the cell’s appearance alone may not convert text into a number.

The result is unexpectedly low or high. Look for zeros, duplicate observations, or values outside the intended range. Check the formula in the first affected result and compare its endpoint with the row number. Also confirm that the values use the same units and that a stray number has not been included above the first observation.

New rows have no running average. Enter the next observation in the row directly below the existing list, then fill the formula down from the row above. If you are using a table, make sure the new row is actually part of the table and check whether Excel copied the calculated column formula. You can also copy the last correct result cell and paste it into the new result cell.

Blank rows make the output confusing. A blank in the source column is ignored by AVERAGE, so the result on that row may repeat the previous running average. If blank rows represent missing observations, that behavior is usually appropriate. If you want results displayed only when the current row has a value, leave the blank-row result empty manually or use a separate display formula designed for that requirement.

Frequently Asked Questions

Does a running average update automatically when I change a value?
Yes. If calculation is set to Automatic, Excel recalculates the affected formulas when you edit a value. Check Formulas > Calculation Options if results appear not to update; choose Automatic if it is not selected.

Does Excel include blank cells in the average?
No. AVERAGE ignores empty cells and text in its referenced range. It does include numeric zeros, so decide whether a zero is a genuine observation or whether the cell should be left empty.

Can I start the running average in a different column or row?
Yes. Put the first result beside the first observation, then reference the first data cell as the fixed start and the current row as the changing end. Adjust both column letters and row numbers to match your worksheet.

What happens if I sort the data?
The formula recalculates using the new row order. Each result then represents the average from the first row in the sorted list through the current row. Sort complete records together so dates, labels, values, and results remain associated.

Can I calculate a running average that ignores zero values?
The basic AVERAGE formula includes zero as a valid number. If zero means no measurement in your data, decide how to represent missing observations consistently before calculating; leaving a missing value blank is one straightforward option. Do not replace real zero measurements with blanks.

Is a running average the same as a moving average?
No. A running average accumulates all numeric observations from the beginning of the series. A moving average uses a fixed recent window, such as the last five values, so older observations eventually drop out of its calculation.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

More in How-to basics

Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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