Drop Frame vs. Non-Drop Frame: What’s the Difference?

If you work in broadcast television or NTSC video, you have likely encountered the confusing terms Drop Frame (DF) and Non-Drop Frame (NDF). Choosing the wrong one can result in your show being rejected by the network or your audio drifting out of sync.

The Core Problem: 29.97 isn't 30

In the NTSC standard (used in the US, Japan, and elsewhere), video runs at 29.97 frames per second. However, standard timecode counts as if there were a nice, round 30 frames per second.

Because the timecode counts slightly faster than the actual video plays, a discrepancy builds up. By the end of one hour, "Non-Drop Frame" timecode will show a duration that is 3.6 seconds incorrect compared to a real wall clock.

Non-Drop Frame (NDF)

In Non-Drop Frame, the timecode counts every single frame sequentially without skipping numbers.

The Visual Clue: NDF usually uses colons between all numbers (e.g., 10:00:00:00).

Use NDF for: Cinema projects, web video, or projects where the total duration doesn't need to match "broadcast time" perfectly.

Drop Frame (DF)

Drop Frame is a correction method. To keep the timecode matching the actual clock on the wall, the counter "drops" (skips) specific frame numbers.

The Drop Frame Rule:

• Skip the first 2 frame numbers (00 and 01) of every minute...
• ...EXCEPT for every 10th minute (00, 10, 20, 30, 40, 50).

The Visual Clue: DF usually uses a semicolon or period before the frames (e.g., 10:00:00;00 or 10:00:00.00).