OneTaskBy Tim King · Updated
Timecode Calculator
Add, Subtract and Convert SMPTE Timecode
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How the Timecode Calculator works
This timecode calculator adds and subtracts SMPTE timecode in HH:MM:SS:FF form at every common frame rate, including 29.97 and 59.94 drop-frame. It also converts a timecode to a total frame count and to real seconds, so you can check durations, offsets and edit points without counting frames by hand.
Timecode labels every frame of a video with hours, minutes, seconds and a frame number. Editors, colourists and sound mixers use it to point at exact frames, but the frame field does not count to 100. At 25 fps it rolls over after frame 24, so ordinary arithmetic gives wrong answers.
How the timecode calculator works
Each timecode is turned into a frame count at the chosen rate. The two counts are added or subtracted, and the result is turned back into timecode. Real time divides the frame count by the true frame rate, so 23.976 and 29.97 results show the small difference from 24 and 30.
You can type a short timecode: 10:00 reads as 10 seconds and 0 frames. Colons, semicolons and full
stops all work as separators.
The timecode formula
For non-drop rates the formula is: frames = ((hours × 60 + minutes) × 60 + seconds) × fps + frames. For drop-frame, subtract 2 × (total minutes − total minutes ÷ 10, rounded down) at 29.97, or 4 × the same at 59.94. Real seconds = frames ÷ true rate, where 29.97 is 30000/1001.
Worked example at 25 fps: 00:59:58:12 is 89,962 frames and 00:00:04:20 is 120 frames. Added, that is 90,082 frames, which is 3,603 seconds and 7 frames: 01:00:03:07.
Worked example at 29.97 drop-frame: 00:00:59;29 is frame 1,799. Add one frame and the count is 1,800. The labels ;00 and ;01 are skipped at minute 1, so the answer is 00:01:00;02.
How many frames are in a given length of video? The table lists frame counts for common durations. The 29.97 and 59.94 columns use the true rate, rounded to the nearest frame.
Frames in common durations by frame rate
| Duration | 24 | 25 | 29.97 | 30 | 59.94 | 60 |
|---|---|---|---|---|---|---|
| 1 second | 24 | 25 | 30 | 30 | 60 | 60 |
| 2 seconds | 48 | 50 | 60 | 60 | 120 | 120 |
| 5 seconds | 120 | 125 | 150 | 150 | 300 | 300 |
| 10 seconds | 240 | 250 | 300 | 300 | 599 | 600 |
| 15 seconds | 360 | 375 | 450 | 450 | 899 | 900 |
| 20 seconds | 480 | 500 | 599 | 600 | 1,199 | 1,200 |
| 30 seconds | 720 | 750 | 899 | 900 | 1,798 | 1,800 |
| 45 seconds | 1,080 | 1,125 | 1,349 | 1,350 | 2,697 | 2,700 |
| 1 minute | 1,440 | 1,500 | 1,798 | 1,800 | 3,596 | 3,600 |
| 90 seconds | 2,160 | 2,250 | 2,697 | 2,700 | 5,395 | 5,400 |
| 2 minutes | 2,880 | 3,000 | 3,596 | 3,600 | 7,193 | 7,200 |
| 3 minutes | 4,320 | 4,500 | 5,395 | 5,400 | 10,789 | 10,800 |
| 5 minutes | 7,200 | 7,500 | 8,991 | 9,000 | 17,982 | 18,000 |
| 10 minutes | 14,400 | 15,000 | 17,982 | 18,000 | 35,964 | 36,000 |
| 15 minutes | 21,600 | 22,500 | 26,973 | 27,000 | 53,946 | 54,000 |
| 20 minutes | 28,800 | 30,000 | 35,964 | 36,000 | 71,928 | 72,000 |
| 22 minutes | 31,680 | 33,000 | 39,560 | 39,600 | 79,121 | 79,200 |
| 30 minutes | 43,200 | 45,000 | 53,946 | 54,000 | 107,892 | 108,000 |
| 45 minutes | 64,800 | 67,500 | 80,919 | 81,000 | 161,838 | 162,000 |
| 1 hour | 86,400 | 90,000 | 107,892 | 108,000 | 215,784 | 216,000 |
| 90 minutes | 129,600 | 135,000 | 161,838 | 162,000 | 323,676 | 324,000 |
| 2 hours | 172,800 | 180,000 | 215,784 | 216,000 | 431,568 | 432,000 |
Drop-frame timecode
NTSC video runs at 30000/1001, about 29.97 frames per second. Counting it as 30 makes timecode drift 3.6 seconds behind the clock every hour. Drop-frame timecode fixes this by skipping frame numbers 00 and 01 at the start of every minute, except every tenth minute. No pictures are dropped, only labels. At 59.94 four numbers are skipped instead of two.
| Rate | Separator | Frame numbers per second | Drift per hour if counted as whole rate |
|---|---|---|---|
| 23.976 | : |
0–23 | 3.6 s |
| 25 | : |
0–24 | none |
| 29.97 drop-frame | ; |
0–29, skipping some | none |
| 29.97 non-drop | : |
0–29 | 3.6 s |
| 59.94 drop-frame | ; |
0–59, skipping some | none |
Tips and pitfalls
Match the rate to the project. The same timecode means a different number of frames at each rate. Check the frame rate in your editor's sequence settings first.
Invalid drop-frame values. In drop-frame, 00:01:00;00 and 00:01:00;01 do not exist. The calculator still accepts them but they map to the same frames as the following valid labels.
Subtraction can go negative. A minus sign in front of the result means the second timecode was later than the first.
How to read the result
The timecode is the answer in the same format. Total frames is useful for frame-accurate tools and scripts. Real time is the clock duration, and frame duration shows how long each frame lasts.
FAQ
How do I add two timecodes?
Enter both as HH:MM:SS:FF, choose Add and pick the frame rate of your project. The calculator turns each into frames, adds them and converts back, carrying frames into seconds at the right point for that frame rate.
What is the difference between drop-frame and non-drop?
Both count the same 29.97 frames each second. Non-drop numbers every frame in sequence, so it runs slow against a clock. Drop-frame skips certain frame numbers so that one hour of timecode equals one hour of real time.
How many frames are in an hour of 29.97 video?
An hour of 29.97 fps video has 107,892 frames. In drop-frame timecode that is exactly 01:00:00;00. In non-drop it shows as 00:59:56:12, because non-drop counts as if each second held thirty frames.
Why does 23.976 real time differ from 24?
23.976 is really 24000/1001 frames per second, so each frame lasts slightly longer than at 24. The timecode labels are the same, but an hour of 23.976 timecode takes about 3.6 seconds longer to play.
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