Question 1

How many frames are in a second at 24fps, 30fps, or 60fps?

Accepted Answer

At 24fps there are 24 frames per second, at 30fps there are 30, and at 60fps there are 60. For the NTSC rates 29.97fps and 59.94fps, each second still contains 30 or 60 actual frames — the ".97"/".94" only affects how many real seconds those frames take to play back, which is exactly why drop-frame timecode exists (see below).

Question 2

What is drop-frame timecode, and when do I need it?

Accepted Answer

Drop-frame timecode only applies to the NTSC rates 29.97fps and 59.94fps, which aren’t whole numbers. If you numbered every frame as if the rate were exactly 30 or 60fps, the displayed timecode would drift about 3.6 seconds ahead of real elapsed time per hour. Drop-frame timecode fixes this by skipping frame *numbers* (2 per minute at 29.97fps, 4 per minute at 59.94fps) at the start of every minute except minutes divisible by 10 — no video frames are actually deleted, only the numbers used to label them. You need it whenever a project’s timecode must match wall-clock duration, which is standard for broadcast delivery.

Question 3

How can a drop-frame timecode be "invalid"?

Accepted Answer

Because drop-frame timecode skips certain frame numbers, some HH:MM:SS:FF combinations never exist. For example at 29.97fps, 00:01:00;00 and 00:01:00;01 are invalid — those two frame numbers were dropped at the start of minute 1. This calculator flags those combinations as invalid input in "Timecode → Frames" mode rather than silently producing a wrong frame count.

Question 4

Why does drop-frame timecode use a semicolon before the frames field?

Accepted Answer

It’s the SMPTE convention: HH:MM:SS;FF (semicolon) signals drop-frame timecode, while HH:MM:SS:FF (colon) signals non-drop-frame. This calculator follows that convention in its output so the result can be pasted directly into edit software or EDLs without ambiguity.

Question 5

How is a frame count converted to a duration in seconds?

Accepted Answer

Duration in seconds = frame count ÷ frame rate. Going the other way, frame count = round(duration in seconds × frame rate), rounded to the nearest whole frame since a fraction of a frame can’t be displayed.

Question 6

Does this calculator upload any files?

Accepted Answer

No. This tool only takes numbers — duration, frame count, timecode, and a frame rate. All conversions run instantly in your browser and nothing is sent to any server.

Video Frame Rate & Timecode Calculator

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Frequently Asked Questions

How many frames are in a second at 24fps, 30fps, or 60fps?

What is drop-frame timecode, and when do I need it?

How can a drop-frame timecode be "invalid"?

Why does drop-frame timecode use a semicolon before the frames field?

How is a frame count converted to a duration in seconds?

Does this calculator upload any files?

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