Duration from an in point and an out point
The length of a shot is its out point minus its in point. The calculator opens with exactly that: the out point on the first line and the in point on a minus line. At 25 fps, 01:07:43:20 minus 01:02:10:05 is 00:05:33:15, which is 8,340 frames or 5 min 33.6 s.
Type your own points over them. Digits fill from the right, so 1074320 reads as 01:07:43:20; no colons needed.
Does the out frame count?
Editing software disagrees about this. Most marks treat the out point as the first frame after the shot, so out minus in is the length. Some edit lists and logging tools mark the last frame of the shot instead; then the length is one frame more, 00:05:33:16 in the example. If your numbers are one frame off from your software, this is why: add a line of 00:00:00:01.
Total length of several clips
To add up clip lengths, put each on its own line with a plus. Four clips at 25 fps, 00:02:14:12, 00:03:05:20, 00:01:47:08 and 00:00:58:15, total 00:08:06:05: 12,155 frames, 8 min 6.2 s. Press Enter in the last box for a new line.
Durations at fractional and drop-frame rates
At 23.976 or 29.97 a timecode duration and a clock duration differ: an hour of 29.97 non-drop labels plays for 1 h 0 min 3.6 s. The calculator shows both, so you can quote whichever a delivery sheet asks for.
Drop-frame needs care across a minute boundary. From 00:00:59;20 to 00:01:00;10 looks like 20 frames, but drop-frame skips two labels in between, so it is 18. Subtracting the labels by hand gets this wrong; the calculator counts real frames. The drop-frame calculator explains the skipping in full.
When the result is negative
If the in point is later than the out point, the result has a minus sign: 00:00:52:00 minus 00:01:00:00 is -00:00:08:00. That usually means the two points are swapped. Switch a line between plus and minus with the button on its left.
The main timecode calculator has every tool on one page, including frames to timecode conversion.
Questions
How do I calculate the duration between two timecodes?
Subtract the in point from the out point at the same frame rate. In the calculator, put the out point on the first line and the in point on a minus line; the result shows the duration, its frame count and its real running time.
Why is my duration one frame different from my editing software?
Some tools count the out point as the last frame of the shot and others as the first frame after it. If yours includes the out frame, add one frame to the result.
Can I add up the lengths of many clips?
Yes. Put each clip length on its own line with a plus. Press Enter in the last box to add another line.
Is a timecode duration the same as real time?
Only at whole rates such as 24, 25 or 30 fps. At 23.976, 29.97 and 59.94 non-drop, timecode runs 3.6 seconds per hour behind the clock; the calculator shows both values.