C# Timecode Conversion

2026-02-02 09:17 UTC gpt-5-2 Open in ChatGPT ↗

You can convert a C# double (time in seconds) into the format:

HH:MM:SS:FF
(hours : minutes : seconds : frames)

Here’s a clean and accurate way to do it.

C# Conversion Method

public static string SecondsToTimecode(double totalSeconds, int fps = 30)
{
    if (totalSeconds < 0)
        totalSeconds = 0;

    int hours = (int)(totalSeconds / 3600);
    int minutes = (int)((totalSeconds % 3600) / 60);
    int seconds = (int)(totalSeconds % 60);

    double fractional = totalSeconds - Math.Floor(totalSeconds);
    int frames = (int)Math.Round(fractional * fps);

    // handle frame rollover
    if (frames >= fps)
    {
        frames = 0;
        seconds++;
        if (seconds >= 60)
        {
            seconds = 0;
            minutes++;
            if (minutes >= 60)
            {
                minutes = 0;
                hours++;
            }
        }
    }

    return $"{hours:00}:{minutes:00}:{seconds:00}:{frames:00}";
}

Example Usage

double timeInSeconds = 3661.52; // 1 hour, 1 minute, 1.52 seconds
string timecode = SecondsToTimecode(timeInSeconds, 30);
Console.WriteLine(timecode);

Output (30 FPS)

01:01:01:16

If You Want 60 FPS Instead

SecondsToTimecode(timeInSeconds, 60);

Breakdown

Part	Meaning
HH	Hours
MM	Minutes
SS	Seconds
FF	Frames (based on FPS)

If you tell me your FPS (24, 30, 60, etc.), I can fine-tune this for broadcast-accurate timecode.