How to use the timecode calculator
- Choose the source rate and DF/NDF counting explicitly. Fractional presets use exact 24000/1001, 30000/1001, 48000/1001, or 60000/1001 rates.
- Convert a label or frame count, add/subtract signed offsets, or measure an In–Out range. For clip points, choose whether the Out frame is included.
- For a clip list, paste Name/In/Out/Rate columns, choose a target timeline and mixed-rate treatment, then calculate. Resolve every row error before copying totals or exporting CSV.
- Read actual playback time separately from the displayed timecode. Review per-clip rounding and speed changes before using the figures in your edit.
Drop-frame versus non-drop-frame
Drop-frame skips labels, not pictures. At 29.97 DF, frame labels ;00 and ;01 at second 00 are skipped every minute except minutes divisible by ten. The sequence goes from 00:00:59;29 to 00:01:00;02. At 59.94 DF with a full-frame counter, ;00 through ;03 are skipped and the next minute begins at ;04.
This workbench rejects skipped labels and delimiter/rate mismatches. DF is available only for 29.97 and 59.94 presets, not 23.976. For rates above 30, the frame field is a full progressive-frame count (00–59 at 59.94/60), not paired-frame LTC/VITC field-bit notation.
Timecode is not wall-clock duration
Timecode counts at a nominal integer base: 24 at 23.976, 30 at 29.97, and 60 at 59.94. For NDF, an hour label at 23.976 or 29.97 takes 3,603.6 playback seconds, not exactly one hour. Elapsed seconds equal frame count multiplied by the rate denominator, divided by its numerator.
At 29.97 DF, 01:00:00;00 is 107,892 frames, lasting 3,599.9964 seconds. DF closely tracks elapsed time but is not mathematically identical to it. Playback clocks are rounded to milliseconds; the copied report includes seconds to nine decimals.
In/Out points and 24-hour wrap
Exclusive Out marks the first frame after a clip: Out − In. Inclusive Out marks the last included frame: Out − In + 1. At 24 fps, In 00:00:00:00 and Out 00:00:00:00 therefore mean zero or one frame respectively. Check the convention used by the editing system or list you are importing.
With midnight wrap enabled, an Out before In is interpreted as one crossing of the 24-hour timecode boundary. Without it, the range is rejected. Conversion and arithmetic also show a wrapped label beside an extended duration and signed timecode-day offset, so results beyond a day are never silently lost. A timecode day is not necessarily 86,400 real seconds at fractional rates.
Mixed-rate conform and rounding
Preserve elapsed time calculates source frames × source denominator × target numerator ÷ (source numerator × target denominator). Each clip is rounded to whole target frames using your chosen rule. The total sums those individually rounded clips and reports how this differs from rounding the combined source duration once.
Preserve frame count keeps every source frame and plays it at the target rate, changing runtime and speed. For example, 240 frames at 24 fps last 10 seconds; the same frames at 25 fps last 9.6 seconds. Neither mode implements pulldown, optical flow, a cadence, or an editor-specific media conform operation.
Frequently asked questions
Can I paste from Excel or Google Sheets?
Yes. Paste Name, In, Out, and optional Rate columns as tabs, or paste comma-separated CSV. Quote names containing commas and double embedded quotes. A Name/In/Out/Rate header is optional. Invalid rows remain visible and block final reports/exports rather than being silently excluded.
Can I add or subtract negative offsets?
Yes, in arithmetic mode. Enter signed timecode or whole signed frames such as -48f. In/Out clock points cannot be negative. Arithmetic results retain their sign; the wrapped clock label is a separate representation.
Why is 00:01:00;00 rejected?
It is a skipped label at 29.97 or 59.94 DF. Enter the actual label for that frame, or select NDF and use a colon if the source uses non-drop counting. The tool does not silently repair a skipped label.
Are these frame-accurate media edits?
This is a numeric planning tool, not a media editor or LTC decoder. It assumes constant frame rates, continuous timecode within each clip, and the selected conventions. Variable-frame-rate footage, timecode breaks, dates across multiple days, field-bit notation, and pulldown need separate treatment.
Technical references
Apple's AVFoundation timecode note explains numbering and drop-frame boundaries. Adobe's XMP timecode types distinguish rate and counting formats. FFmpeg's public timecode implementation provides an interoperability reference for NTSC label adjustment and high-frame-rate field notation. The workbench uses its own arithmetic and is tested against independent frame-by-frame label sequences.