How to get the Unix timestamp in C#

A Unix timestamp is a system for describing time as the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC. This epoch time is widely used across different operating systems and programming languages for consistent time representation.

Unix timestamps are particularly useful for storing dates in databases, comparing times across different time zones, and working with APIs that expect epoch time values.

What is Unix Timestamp?

The Unix timestamp represents time as a single integer value − the count of seconds since the Unix epoch (January 1, 1970, UTC). This makes it timezone-independent and easy to work with programmatically.

Using DateTime.Now.Subtract() Method

The traditional approach calculates the difference between the current time and the Unix epoch −

using System;

class Program {
   static void Main(string[] args) {
      Int32 unixTimestamp = (Int32)(DateTime.Now.Subtract(new DateTime(1970, 1, 1))).TotalSeconds;
      Console.WriteLine("The Unix Timestamp is {0}", unixTimestamp);
   }
}

The output of the above code is −

1596837896

Using DateTimeOffset.ToUnixTimeSeconds() Method

The modern and recommended approach uses the built-in ToUnixTimeSeconds() method −

using System;

class Program {
   static void Main(string[] args) {
      var unixTimestamp = DateTimeOffset.Now.ToUnixTimeSeconds();
      Console.WriteLine("The Unix Timestamp is {0}", unixTimestamp);
   }
}

The output of the above code is −

1596819230

Using TimeSpan Struct Methods

An alternative approach using TimeSpan for calculating the difference in ticks −

using System;

class Program {
   static void Main(string[] args) {
      TimeSpan epochTicks = new TimeSpan(new DateTime(1970, 1, 1).Ticks);
      TimeSpan unixTicks = new TimeSpan(DateTime.Now.Ticks) - epochTicks;
      Int32 unixTimestamp = (Int32)unixTicks.TotalSeconds;
      Console.WriteLine("The Unix Timestamp is {0}", unixTimestamp);
   }
}

The output of the above code is −

1596839083

Converting Unix Timestamp Back to DateTime

You can also convert a Unix timestamp back to a readable date format −

using System;

class Program {
   static void Main(string[] args) {
      long unixTimestamp = 1596819230;
      
      // Convert to DateTime
      DateTime dateTime = DateTimeOffset.FromUnixTimeSeconds(unixTimestamp).DateTime;
      Console.WriteLine("Unix timestamp {0} converts to: {1}", unixTimestamp, dateTime);
   }
}

The output of the above code is −

Unix timestamp 1596819230 converts to: 8/7/2020 2:40:30 PM

Comparison of Methods

Conclusion

Getting Unix timestamps in C# can be accomplished through multiple methods. The DateTimeOffset.ToUnixTimeSeconds() method is the most modern and recommended approach, while DateTime.Subtract() provides compatibility with older .NET versions. Choose the method that best fits your project requirements and .NET version.