Subtitle Timing Calculator
Six small calculators for subtitle work: convert timecodes and frames, add and subtract times, measure durations, convert frame rates, work out a sync offset and find the reading time of a text. No file needed.
- Six calculators
- Frames to timecode
- Copy any result
- Free
Examples: 00:01:30,500 · 90.5 · 1500ms · 00:01:30:12 (frames) · 2263f
Where a moment ends up when a film is converted between frame rates (PAL speed-up, NTSC pull-down).
First line of dialogue
A line near the end (optional)
One point gives the delay to apply. Two points also show whether the subtitles drift — the sign of a different frame rate.
How to use the timecode calculator
Results appear as soon as the values are entered.
- 1
Pick a calculator
Choose between timecode conversion, adding and subtracting, duration, frame-rate conversion, sync offset and reading time.
- 2
Enter the values
Type a timecode, a number of frames or a text, and select the frame rate where one is needed, from 23.976 to 60 fps.
- 3
Copy the result
Every result has its own Copy button, so the value can be pasted straight into a subtitle file or an editor.
Six calculators for subtitle timing
The sums that come up while timing, converting and syncing subtitles.
Timecode converter
One timecode shown as SRT, WebVTT, ASS, milliseconds, seconds, frames and SMPTE timecode.
Frames and drop-frame
Frames to timecode at nine frame rates, with drop-frame SMPTE timecode for 29.97 and 59.94 fps.
Add and subtract
Add or subtract times without doing the base-60 arithmetic by hand.
Duration
Time between two timecodes, also in frames, and the characters that fit at 17 and 20 CPS.
Frame-rate conversion
Convert a time between frame rates such as 23.976 and 25 fps, with speed factor and drift per hour.
Sync offset
Compare subtitle time and real time at one or two points to get the shift and the speed factor.
Reading time
The minimum duration a text needs at the CPS limit you choose.
Copy buttons
Each result can be copied with one click; nothing is uploaded and no file is required.
How do you convert frames to timecode and back?
The same moment is written differently in every subtitle format. SRT puts a comma before the milliseconds (00:01:30,500), WebVTT a dot (00:01:30.500), ASS uses a single hour digit and hundredths of a second (0:01:30.50), and video editors count frames or show SMPTE timecode (00:01:30:12 at 24 fps). The timecode calculator turns one value into all of these at once, which avoids the usual slips with commas, dots and frame numbers.
Frames only mean something together with a frame rate: frame 2172 is 1 minute 30.5 seconds at 24 fps but about 1 minute 26.9 seconds at 25 fps. At 29.97 and 59.94 fps, drop-frame timecode skips a few frame numbers, two per minute at 29.97 fps except in every tenth minute, so that the timecode keeps pace with the clock. No picture is dropped. Drop-frame timecode is written with a semicolon before the frames.
When subtitles are out of sync, two measurements show why. If the difference between subtitle time and spoken time is the same at the start and near the end, it is a constant offset. If it grows, it is drift, most often a frame-rate mismatch: a film made at 23.976 fps and played at 25 fps runs about 4 % faster (factor 1.0427), roughly 2.5 minutes per hour. The sync offset calculator shows the shift, the speed factor and whether it looks like such a mismatch.
One moment (1 min 30.5 s) in different notations
| Notation | Written as | Where it is used |
|---|---|---|
| SRT | 00:01:30,500 | SubRip files, most players and TVs |
| WebVTT | 00:01:30.500 | HTML5 video and web players |
| ASS / SSA | 0:01:30.50 | Aegisub and styled subtitles |
| Milliseconds | 90500 | Scripts and subtitle delay settings |
| Frames at 24 fps | 2172 | Frame-based formats and video editors |
| SMPTE at 24 fps | 00:01:30:12 | Editing and broadcast software |
Tips
- If the offset is the same everywhere, apply the calculated shift with SRT Time Shift, or use Subtitle Delay for small corrections in milliseconds.
- If the calculator reports a speed factor or a frame-rate mismatch, a shift is not enough. SRT Sync corrects the drift with two sync points or a frame-rate conversion.
- The reading-time calculator handles one text. To check every subtitle of a file against a CPS limit, open it in the Subtitle CPS Calculator.
- Check the real frame rate of the video before converting frames. 23.976 and 24 fps look alike, yet they drift apart by about 3.6 seconds per hour.
Frequently asked questions
Can’t find your answer? Contact us — we reply quickly.
How do I convert frames to timecode?
Divide the frame number by the frame rate to get seconds: 2172 frames at 24 fps are 90.5 seconds, or 00:01:30,500 in SRT. The calculator does this for nine frame rates from 23.976 to 60 fps and in both directions.
What is drop-frame timecode?
At 29.97 fps a timecode that counts 30 frames per second slowly falls behind the clock. Drop-frame timecode skips frame numbers 00 and 01 at the start of every minute, except every tenth minute, to stay in step. Only numbers are skipped, not pictures.
What is the difference between SRT and WebVTT timecodes?
SRT writes 00:01:30,500 with a comma before the milliseconds and always includes the hours. WebVTT uses a dot, 00:01:30.500, and the hours may be left out.
How long is a gap of 2 frames?
About 83 milliseconds at 24 fps and 80 milliseconds at 25 fps. Two frames are the minimum gap between subtitles in the Netflix guidelines.
Why do my subtitles drift further out of sync during the film?
The subtitles were probably timed for a version with a different frame rate, typically 25 fps against 23.976 fps. The delay then grows by about 2.5 minutes per hour. Enter two points in the sync offset calculator to confirm it.
Do I need to open a subtitle file?
No. All six calculators work with values you type in. Everything runs in your browser, nothing is uploaded, and the tool is free.
More free subtitle tools
View, edit, convert, sync and check subtitles — fast, free and private, right in your browser.