How to convert seconds into hh:mm:ss in C#?

If you are using .NET 4.0 or above, you can simply convert seconds into TimeSpan and then get hours:minutes:seconds

TimeSpan time = TimeSpan.FromSeconds(seconds);

// backslash is used to ":" colon formatting you will not see it in output
string str = time.ToString(@"hh\:mm\:ss");

Here is the sample Program

using System;
					
public class Program
{
	public static void Main()
	{
		TimeSpan time = TimeSpan.FromSeconds(890);

		// backslash is used to ":" colon formatting you will not see it in output
		string str = time .ToString(@"hh\:mm\:ss");
		Console.WriteLine(str);
	}
}

Output:

00:14:50

You can try it on .NET fiddle: https://dotnetfiddle.net/mMsjxH

If you want to add "miliseconds" also, then use below format

string str = time.ToString(@"hh\:mm\:ss\:fff");

You can also simply use TimeSpan.FromSeconds(90) where 90 = total number of seconds, this code will convert seconds into hh:mm:ss

Here is the Sample C# Code

using System;
					
public class Program
{
	public static void Main()
	{
		Console.WriteLine(TimeSpan.FromSeconds(90));
	}
}

Output:

00:01:30

Hope it helps, thanks.