DateTime - ConvertTimeToUtc

Converts the time in a specified time zone to Coordinated Universal Time (UTC).

Try it

public static void Main()
{
    DateTime thisTime = DateTime.Now;
    Console.WriteLine("Time in {0} zone: {1}", TimeZoneInfo.Local.StandardName, thisTime);
	
	// C# Extension Method: DateTime - ConvertTimeToUtc
    Console.WriteLine("   UTC Time: {0}", thisTime.ConvertTimeToUtc(TimeZoneInfo.Local));

    // Get Tokyo Standard Time zone
    TimeZoneInfo tst = TimeZoneInfo.FindSystemTimeZoneById("Tokyo Standard Time");

	// C# Extension Method: DateTime - ConvertTime
    DateTime tstTime = thisTime.ConvertTime(TimeZoneInfo.Local, tst);
    Console.WriteLine("Time in {0} zone: {1}", tst.StandardName, tstTime);

	// C# Extension Method: DateTime - ConvertTimeToUtc
    Console.WriteLine("   UTC Time: {0}", tstTime.ConvertTimeToUtc(tst));
}

View Source
using System;

public static partial class Extensions
{
    /// <summary>
    ///     Converts the current date and time to Coordinated Universal Time (UTC).
    /// </summary>
    /// <param name="dateTime">The date and time to convert.</param>
    /// <returns>
    ///     The Coordinated Universal Time (UTC) that corresponds to the  parameter. The  value&#39;s  property is always
    ///     set to .
    /// </returns>
    public static DateTime ConvertTimeToUtc(this DateTime dateTime)
    {
        return TimeZoneInfo.ConvertTimeToUtc(dateTime);
    }

    /// <summary>
    ///     Converts the time in a specified time zone to Coordinated Universal Time (UTC).
    /// </summary>
    /// <param name="dateTime">The date and time to convert.</param>
    /// <param name="sourceTimeZone">The time zone of .</param>
    /// <returns>
    ///     The Coordinated Universal Time (UTC) that corresponds to the  parameter. The  object&#39;s  property is
    ///     always set to .
    /// </returns>
    public static DateTime ConvertTimeToUtc(this DateTime dateTime, TimeZoneInfo sourceTimeZone)
    {
        return TimeZoneInfo.ConvertTimeToUtc(dateTime, sourceTimeZone);
    }
}