What this calculator does
This tool performs frame-accurate timecode arithmetic, the same way an Avid, Premiere Pro or DaVinci Resolve timeline does internally: every timecode is converted to a total frame count, the math is done on frames, and the result is converted back to timecode at your selected rate. That means additions and subtractions are always exact — including across the tricky drop frame boundaries at 29.97 and 59.94 fps.
Typical jobs it handles in seconds:
- Working out the duration between two timecodes on a source tape or camera card
- Calculating an end-credit start point from a program duration spec
- Adding handles to in/out points for a pull or conform
- Converting a frame count from an EDL, subtitle file or QC report into a readable timecode
- Spotting sound: turning a mix stem length in frames into session timecode
Drop frame, explained properly
At 29.97 fps, video runs 0.1% slower than true 30 fps. If timecode simply counted 30 frames per second, the displayed "hour" would drift about 3.6 seconds behind the wall clock every hour — a problem for broadcast, where program durations are contractual. Drop frame timecode fixes the drift by skipping frame numbers 00 and 01 at the start of every minute, except minutes 00, 10, 20, 30, 40 and 50. Over one hour that skips 108 numbers, bringing the count back in line with real time (to within 3 frames per day).
No pictures are ever thrown away — drop frame only changes the labels, never the video.
You can spot drop frame timecode by its separator: 01:00:00;02 (semicolon) is drop
frame, 01:00:00:02 (colon) is non-drop. This calculator implements the standard SMPTE
drop frame algorithm, so results match what you see in Avid Media Composer, Premiere Pro and Resolve.
Supported frame rates
| Rate | Where you meet it | Timecode counting |
|---|---|---|
| 23.976 | Digital cinema cameras, streaming masters | Counts as 24, runs 0.1% slow — no DF variant exists |
| 24 | True film, DCP | Exact |
| 25 | PAL broadcast (Europe, China, Australia) | Exact — drop frame never applies |
| 29.97 DF / NDF | NTSC broadcast (US, Japan) | DF for broadcast deliverables, NDF common in post |
| 30 / 50 / 59.94 / 60 | High frame rate acquisition, sports, screens | 59.94 has DF and NDF variants like 29.97 |
FAQ
What is the difference between drop frame and non-drop frame timecode?
Non-drop frame (NDF) timecode counts every frame sequentially. Drop frame (DF) timecode skips frame numbers 00 and 01 at the start of every minute — except every tenth minute — so that the timecode display stays in step with real clock time when shooting at 29.97 fps. No actual video frames are ever dropped; only the numbering skips.
Why does 29.97 fps exist instead of just 30 fps?
When color was added to the American NTSC television standard in 1953, engineers slowed the frame rate by 0.1% (30 ÷ 1.001 ≈ 29.97) to prevent interference between the color and audio signals. That legacy rate survives today in broadcast delivery specs, which is why drop frame timecode is still required for many US broadcast masters.
When should I use drop frame timecode?
Use drop frame when your delivery spec requires program duration to match real time — typically US/NTSC broadcast television at 29.97 or 59.94 fps. Use non-drop frame for most film, streaming, and online work at 23.976, 24, or 25 fps, or when your post-production pipeline specifies it.
How do I add two timecodes together?
Convert each timecode to a total frame count, add the frame counts, then convert the sum back to timecode at the same frame rate. That is exactly what this calculator does — including the drop frame adjustment when you select 29.97 DF or 59.94 DF.
Does 23.976 fps timecode use drop frame?
No. There is no drop frame variant for 23.976 fps. Timecode at 23.976 counts frames 00–23 like true 24 fps, which means one "hour" of 23.976 timecode is actually about 3.6 seconds longer than a real hour. This calculator shows you the real running time so you can account for the difference.