Using the Avid Calculator

If you avoid its longstanding quirks, it can be a useful tool.

by Robert Brakey & Steve Cohen

The Avid calculator has been around for a long time, but because its' controls are confusing, many people never use it. If you know what you are doing, however, it can be very valuable, helping you to measure your show either in feet or timecode. The calculator is under the 'Tools' menu and looks like this:

The window is divided into panes: at the top, a format pop-up menu, on the left a text entry area and keypad, on the right, a record of your calculations that simulates a paper tape.

The most confusing and yet most important part of the calculator is the popup menu at the top (you won't know it's a pop-up until you click on it). With this menu you determine the way entered numbers are interpreted (either as time or as footage) and by making different selections, you also use this menu to make conversions (footage to time, drop-frame to non-drop-frame, and so on). Click on the menu to open it:

At the top are a variety of frame rates and following that are frame per edge-number selections. 35mm projects use 16 'Frames/Edge' and 16mm projects will use either 40 or 20 'Frames/Edge'. At the bottom of the list is a selection for total frame count.

This article will demonstrate the use of the calculator through two examples: how to add reel footages and convert them to time, and how to add a list of timecodes or act timings.

Adding Footages and Converting to Time

This is one of the most common things film editors and assistants will do with the calculator. You'll measure your reels using center duration or master footage, then total those numbers and convert them to time using the calculator.

Before you can enter numbers into the calculator, you must tell it the format of the numbers you'll type. Begin by selecting '16 frames/edge (35mm)'.

Next, enter your footages. You can do this with your mouse and the calculator's numeric keypad, but if you would rather go home at a decent hour, use the numeric keypad on your keyboard. Keep in mind that you must enter the full number, including both digits for the frames, without punctuation. If your footage is 988 feet and 4 frames, you must enter 98804. Do not type a plus sign. The calculator will include it for you and show you how it is interpreting your numbers in the display below the popup:

Enter the complete first number including a two digit frame count, then press the plus sign and key in another number (just as you would in a conventional calculator). If you make a mistake clear your entry by hitting the 'CE' key (clear entry) with the mouse. Don't try to edit the number in the on-screen display-this will produce unpredictable results. Continue adding numbers in this way until you've entered all your footages. Then press enter to see a total. As you add footages, the display will show the current total, while the tape on the right will provide a full record of your calculations (unfortunately, you can't print it).

Here's what the calculator looks like after totaling five footages: 988+12, 766+06, 832+15, 944+09 and 786+12. Each subtotal is displayed separately on the tape.

We now want to convert this total to time. To do this we simply select the correct time format from the popup menu. But which to choose? It might seem intuitive to choose '30 Drop'. After all, when we display the clock length of our show we do it in drop frame, don't we? In fact this is not the correct choice and will produce the wrong answer every time. What we want is '24 FPS'-this will produce the running time of the show when played at 24 frames per second.

Your calculator will now display the total length of your show in hours:minutes:seconds and film frames.

Note that when adding film footages and converting to time the calculator will only convert correctly at 24 fps. This is the same as the standard formula we've all learned, 90 feet = 60 seconds, and should suffice in almost all situations. It's the answer people normally expect to the question 'how long is my show'.

However, when your show is transferred to tape it actually gets slightly longer than this because film is transferred to tape at 23.976 fps (one tenth of one percent longer). The calculator will not directly give you this length. But if you are determined, you can trick it into making the conversion. First enter and add your footages as indicated above and convert to time at 24 fps. Write down the total. Then convert the frame count from your total to video frames using the following formula: video frames = film frames x 1.25. Clear the calculator by hitting the clear button ('CL') and reset the popup to '30 Non-Drop'. Enter the number you wrote down, replacing the film frame count with the video frame count. Now switch the popup to '30 Drop'. The result will be the television timing of your show.

Adding Act Timings

Next we'll add several video timings. As before, we must first tell the calculator the format of our numbers before we begin to enter them. We'll assume that you've standardized your sequence lengths as either drop or non-drop timecode. (The Film Composer defaults new sequences to non-drop frame. To change this to drop frame, load the sequence, click on the record monitor, select 'Get Clip Info' from the File menu, and change the timecode punctuation in the 'Start' window-colons for non-drop, semi-colons for drop frame).

For this example we'll assume that your sequences are being measured in non-drop format (colons), so select '30 Non-Drop' from the calculator popup.

Now enter and add the timecode durations of your sequences, making sure to type no punctuation. To enter 01:10:24:00, type 01102400. You can enter a double zero in one keystroke by hitting the period key on the numeric keypad. Enter each duration, press the plus sign and key in the next number. Press enter for the final total. Here's the calculator after adding four measurements, 00:10:24:15, 00:09:41:22, 00:08:57:05 and 00:10:12:09.

Final Thoughts

Always add your numbers twice in order to check for accuracy. It's just too easy to make a typo. If you add a column of numbers twice and get the same answer both times you can have some confidence that you entered the numbers correctly.

The calculator hasn't changed much in the many years since its inception. In effect, its still in version 1. One bug has been fixed, however. It used to produce erroneous footage to time conversions for anything longer than 10,000 feet. Thankfully, this has now been fixed. It now makes correct conversions for footage totals up to 65,535 feet (64k feet) or a little over 12 hours (12:08:10:00). Lengths greater than that will still produce erroneous results.

Robert Brakey has been working on the AVID Film Composer for 7 years.
He is currently the first assistant to Alan Heim on
'Bless The Child' for Paramount Pictures. He can be reached via

Steve Cohen is a Guild Board member, news editor of the Guild home page
and interim editor of the Newsletter. He is currently cutting 'Fifteen Minutes' for New Line.
He can be reached via

Reprinted from
The Motion Picture Editors Guild Newsletter
Vol. 21, No. 1 - Jan/Feb 2000

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