FPS Timecode Calculator

FPS timecode calculator

Video editors and motion-graphics artists work in timecode — HH:MM:SS:FF, where the last field counts individual frames. This calculator translates a timecode at a chosen frame rate into a total frame count and the real elapsed time, which is essential for editing, conforming footage, and spotting the drift caused by fractional NTSC rates.

Why timecode exists

A wall clock measures time in seconds, but video editors need precision down to individual frames. A second at 24 fps contains 24 distinct frames; a second at 60 fps contains 60. Without the frame field (FF), a time like 00:01:30 would be ambiguous by up to a full second — which frame within that second is the cut point?

Timecode (HH:MM:SS:FF) solves this by appending the frame count within the current second. At 25 fps, 00:01:30:12 means the 13th frame (frames are zero-indexed) of the 90th second — a precise location in the clip that any editor or system can find reproducibly.

Timecode is also how synchronisation works in multi-camera shoots: all cameras lock to the same timecode source, making it trivial to align footage in post.

The NTSC fractional rate problem

The most confusing aspect of timecode is the gap between the labelled frame rate and the actual frame rate for NTSC-family footage.

When colour television was introduced in the US, the frame rate was reduced slightly from 30 fps to approximately 29.97 fps to avoid interference between the colour subcarrier and the audio subcarrier. The resulting rate is exactly 30,000/1,001 fps.

The timecode format was kept as HH:MM:SS:FF with a 30-frame field (0–29), but the clock it represents is now running slightly slower than real time. Over a one-hour programme, this creates a drift of about 3.6 seconds between the timecode clock and actual elapsed time.

Drop-frame timecode was invented to compensate: it skips frame numbers 00 and 01 at the start of every minute except every tenth minute, keeping the timecode clock close to real time. This is why you see timecode written with semicolons (01;00;00;00) for drop-frame and colons (01:00:00:00) for non-drop-frame.

This calculator works with non-drop-frame timecode and shows both total frames and the actual elapsed time based on the true fractional rate.

How it works

The tool first counts how many frames the timecode represents:

frames = ((HH × 60 + MM) × 60 + SS) × fps + FF

It then derives the real elapsed time by dividing that frame count by the true fractional rate. At 29.97, for example, 1,000 frames of timecode represents 1000 / 29.97 ≈ 33.37 real seconds, not exactly 33.33.

Worked example

At 25 fps, the timecode 00:01:30:12:

seconds  = (0 × 60 + 1) × 60 + 30 = 90
frames   = 90 × 25 + 12 = 2,262 frames
real time = 2,262 ÷ 25 = 90.48 seconds

All calculations happen entirely in your browser — nothing is uploaded.