Timecode Calculator

Add and subtract timecodes, or convert between timecode and frames, with full drop-frame support.

How to use the Timecode Calculator

  1. Choose the frame rate.
  2. Choose the operation.
  3. Enter the timecode a (hh:mm:ss:ff).
  4. Enter the timecode b (hh:mm:ss:ff).
  5. Enter the frame count.
  6. Press Calculate. The result updates automatically as you type.

About the Timecode Calculator

SMPTE timecode labels every frame as hours:minutes:seconds:frames. At whole-number rates such as 24, 25 and 30 fps, the label matches the clock exactly. NTSC-derived rates run 0.1% slow (29.97 instead of 30), so counting 30 labels per second slowly drifts from real time, by about 3.6 seconds per hour.

Drop-frame timecode fixes that drift by skipping frame numbers 00 and 01 (or 00–03 at 59.94) at the start of every minute except each tenth minute. No pictures are dropped, only labels. Drop-frame is shown with a semicolon before the frames. Use it for broadcast deliverables where program length must match the clock; non-drop is common in film and online video workflows.

Formula

Non-drop frames = (H × 3600 + M × 60 + S) × fps + F
Drop-frame frames = same − d × (total minutes − ⌊total minutes ÷ 10⌋)

Here fps is the nominal rate (24, 25, 30 or 60) and d is 2 for 29.97 and 4 for 59.94. Real duration = frames ÷ true frame rate (for example 30000/1001). Adding 00:10:00;00 and 00:00:30;15 at 29.97 DF gives 17,982 + 915 = 18,897 frames, which displays as 00:10:30;15.

Example calculation

Using the default values:

  • Frame rate = 29.97 fps drop-frame
  • Operation = Add two timecodes
  • Timecode A (HH:MM:SS:FF) = 00:10:00:00
  • Timecode B (HH:MM:SS:FF) = 00:00:30:15

the calculator returns:

  • Timecode: 00:10:30;15
  • Total frames: 18,897
  • Real (wall-clock) duration: 10 min 30.53 s

Frequently asked questions

What is the difference between drop-frame and non-drop timecode?

Both count the same frames. Drop-frame skips certain frame numbers so the displayed time matches the wall clock at 29.97 or 59.94 fps; non-drop does not, so it runs about 3.6 s per hour behind.

How many frames are in 10 minutes of 29.97 drop-frame?

17,982 frames, which is exactly 10 minutes of 30000/1001 fps video to within a fraction of a frame.

Is 23.976 fps drop-frame?

No. There is no drop-frame standard for 23.976; it always uses non-drop timecode counted at 24 labels per second.

Last updated: · Category: TV & Video calculators

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