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About this tool
Add up a list of clip durations in mixed formats and see total runtime, average length and how it fits a target slot.
Total runtime is simply the sum of every clip length plus any padding between them, but only once each duration has been converted to the same unit. This calculator normalises mixed notation — 1:30, 00:02:15, plain seconds, 1m 20s and SMPTE hh:mm:ss:ff — into seconds, adds them, and reports the total in clock time, seconds, minutes and frames alongside the average and median clip length and the gap to a target slot.
Open Runtime Sum Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Stopwatch readings, clock times, bare seconds and timecode can all sit in the same paste.
Padding is applied between clips only, so ten clips get nine gaps, not ten.
The result states how far over or under the slot you are, in both time and percentage.
Convert each length to seconds, add them, then convert the total back to hh:mm:ss. Two clips of 1:30 and 2:15 are 90 + 135 = 225 seconds, which is 00:03:45. Mixing minutes and seconds without converting first is the usual source of error.
In commercial broadcast a 30-minute slot typically carries about 21 to 22 minutes of programme, and a 60-minute slot about 42 to 44 minutes, with the rest given to advertising and station idents. The exact figure is set by the broadcaster's delivery specification, so confirm it before locking the edit.
It is the frame count within that second, so its value depends on the frame rate. At 25 fps, 12 frames is 12 ÷ 25 = 0.48 seconds, making the clip 10.48 seconds; the same label at 30 fps would be 10.4 seconds.
Only if they add time. A cross-dissolve that overlaps two clips shortens the total, while a black gap or a stinger between items lengthens it — use the gap field for the latter and shorten the individual clip lengths for the former.
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