Common Shares Outstanding Calculator for Calculating Weighted Average

Stock Shares Outstanding Calculator Sign

This free online Stock Shares Outstanding Calculator will calculate the weighted average for a company that changes its number of outstanding shares during the period in which you are interested.

Unlike most textbooks that limit their examples to the number of months, this calculator measures durations in the number of days.

Plus, after calculating the weighted average, the calculator will generate a line-by-line summary of each transaction.

Note that the results of this calculator are most commonly used for calculating the Earnings Per Share (EPS).

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Stock Shares Outstanding Calculator

Calculate common shares outstanding using the weighted average method.

Special Instructions

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Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None
Begin shrs:Begin shares:Beginning shares outstanding:Beginning shares outstanding:

Beginning shares outstanding:

Enter the number of beginning shares outstanding and then select the beginning date in the row directly below this one.

Beginning date:Beginning date:Beginning date:Beginning date:

Beginning date:

Select the beginning month, day, and year. Note that this date selection will need to come before all other dates selected in the remainder of the calculator.

Ending date:Ending date:Ending date:Ending date:

End date:

In the row directly below this line, select the ending date of the period you are calculating outstanding shares for. Note that all selected dates must be earlier than this date.

Interim Stock Transactions

Interim Stock Transactions:

Use this section to enter the stock transactions that occurred between the beginning and ending dates selected above. Note that the calculator will attempt to sort the transactions in chronological order (from earliest to latest), but it would be best if you entered them in that order.

To add a transaction, select the date of the transaction (must be unique from all other transaction dates), select Increase or Decrease, and enter the number of shares transacted. When you're satisfied with the selections and entries, tap the Add ... button.

To edit a transaction, click its numbered Edit button to load the transaction into the form. When you're done making changes, tap the Save ... button.

To delete a transaction, click its numbered Edit button to load the transaction into the form. Then click the Del... button.

Important! In order to save your entries for your next visit, you will need to create (or save an existing) data record under the Data tab before closing or leaving this page.

Transaction date:Transaction date:Transaction date:Transaction date:

Transaction date:

Select the the date of the transaction. Note that the date must fall within the selected beginning and ending dates, and it must be different from any and all other transaction dates. If two or more stock transactions occurred on the same date, please combine them into a single entry.

Effect:Effect:Increase or decrease:Increase or decrease:

Increase or decrease:

Select whether the transaction resulted in an increase or a decrease in the total common shares outstanding.

Trans shrs:Trans shares:Transaction shares:Transaction shares:

Transaction shares:

Enter the number of shares associated to the transaction.

Total days:Total days:Total number of days:Total number of days:

Total number of days:

This is the calculated number of days from the beginning date to the ending date.

End shares:Ending shares:Ending shares outstanding:Total ending shares outstanding:

Total ending shares outstanding:

This is the number of shares outstanding after the beginning and all entered stock transactions have been accounted for.

Avg shares:Avg shares:Weighted average shares:Weighted average number of outstanding shares:

Weighted average number of outstanding shares:

This is the weighted average of the shares outstanding from the beginning date to the ending date.

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

Help and Tools


What weighted average is, how to calculate it, and how it compares to simple average.

What is Weighted Average?

A weighted average is a calculation used to give more weight to more influential values within a data set, and lower weight to values with less influence.

As it relates to shares of outstanding stock, the weighted average calculation gives greater weight to larger numbers of outstanding shares and longer durations and gives less weight to the smaller number of shares and shorter durations.

Weighted Average Vs Simple Average

To illustrate the difference between simple average and weighted average, suppose a company has 10,000 shares outstanding at the beginning of the year and 20,000 shares outstanding at the end of the year. Using a simple average formula, the average number of shares outstanding would be 15,000 (30,000 ÷ 2 = 15,000).

However, if the year-end share increase were due to a stock split that occurred on December 15th of the year, the 15,000 simple average result would not accurately reflect the day-to-day average for the entire year.

The following results from the calculator on this page show how the weighted average calculation more accurately reflects the day-to-day average of outstanding shares.

Date Range
1/1/13 - 12/15/1310,00034895.34%9,534
12/15/13 - 12/31/1320,000164.38%877
Weighted average outstanding shares »10,411

See how weighted average more accurately reflects the outstanding day-to-day shares during the year?

How to Calculate Weighted Average Shares Outstanding

Here are the steps to calculate the weighted average of the number of shares outstanding based on durations stated in the number of days:

  1. Count the total number of days from the beginning date to the ending date. If the total duration is a full calendar year (January 1 - December 31), then the total number of days would be 365 (or 366 for leap years).
  2. For each period containing a different number of outstanding shares, count the number of days in the period (column C in the example) and divide that result by the total number of days (results in column D expressed as percentages).
  3. For each period, multiply the decimal result arrived at in step #2 by the number of shares outstanding during the applicable timeframe (results in column E above).
  4. Add up all of the results arrived at in step #3 (sum of column E in example). That sum is then equal to the weighted average number of outstanding shares.

Note that if you find yourself trying to calculate weighted average manually, it will be easier -- though less accurate -- to work with durations stated in months. In that case, you would divide the number of months in each change in outstanding shares by the total months to arrive at the percentages in column D above.

Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.