C# / .NET - get current time in milliseconds

In this short article, we would like to show how to get current time in milliseconds in C# / .NET.

Motivation: the most common way in different systems to present time in milliseconds is UNIX timestamp that is measured as milliseconds elapsed from 1970-01-01 (e.g. JavaScript Date class that uses that time).

Quick solution:

DateTime unixEpoch = new DateTime(1970, 1, 1);

DateTime currentTime = DateTime.UtcNow;
TimeSpan elapsedTime = date.Subtract(currentTime);

long unixTimstamp = (long)elapsedTime.TotalMilliseconds;  // <--- unix timstamp in milliseconds

1. Custom Unix milliseconds timestamp example

In this section, we have prepared reusable code that returns Unix time.

public static class TimeUtils
{
	public static long GetUnixTimstamp(DateTime date)
	{
		DateTime zero = new DateTime(1970, 1, 1);
		TimeSpan span = date.Subtract(zero);

		return (long)span.TotalMilliseconds;
	}

	public static long GetUnixTimstamp()
	{
		return GetUnixTimstamp(DateTime.UtcNow);
	}
}

Example:

Console.WriteLine(TimeUtils.GetUnixTimstamp());

Output:

1565647530865

2. .NET 4.6 API Unix milliseconds timestamp example

.NET +4.6 introduced some API that lets to get Unix time in easy way.

DateTimeOffset now = (DateTimeOffset)DateTime.UtcNow;

Console.WriteLine(now.ToUnixTimeMilliseconds());

Output:

1565647040281

3. Custom milliseconds timestamp example

Ticks are measured from 12:00:00 midnight, January 1, 0001 in the Gregorian Calendar.

long time = DateTime.Now.Ticks / TimeSpan.TicksPerMillisecond;

Console.WriteLine(time);

Output:

63701247264339

Note: be careful using this example, because time here is not measured from 1970-01-01.

References:

1. DateTime Class - Microsoft Docs
2. DateTimeOffset.ToUnixTimeMilliseconds Method - Microsoft Docs