We looked at the new DateOnly Type on Day 1 of this series, and it should come as no surprise that there is a companion TimeOnly type that has been introduced to deal with only the time component of a DateTime.

There are three constructors, depending on the accuracy of the time you want:

// Create the time 9.30 with varying levels of detail
var time = new TimeOnly(9, 30);
var timeWithSeconds = new TimeOnly(9, 30, 30);
var timeWithMilliSeconds = new TimeOnly(9, 30, 30, 99);

There is also a constructor that takes Ticks as a parameter. Ticks in this instance would refer to every 100 nanoseconds since 00:00:00.0000000

var time = new TimeOnly(100);

You can also obtain a TimeOnly from a TimeSpan, using the FromTimeSpan method.

var span = TimeSpan.FromMinutes(10);
var timeFromSpan = TimeOnly.FromTimeSpan(span);

I expect there may be some confusion between these two types because the TimeSpan is currently how the DateTime deals with the time element. Additionally, a TimeSpan refers to a time interval.

You can also obtain a TimeOnly from a DateTime using the FromDateTime static method.

var now = TimeOnly.FromDateTime(DateTime.Now);

The TimeOnly type operates using the 24 hour clock, so midnight is 00:00 and noon is 12:00.

With a TimeOnly object you can perform the expected manipulations.

For example, if you would like to know what the Time would be one hour, thirty minutes form now:

var future = TimeOnly.FromDateTime(DateTime.Now)

For some reason there isn’t an AddSeconds or AddMilliseconds method!

But if you wanted to add an additional 5 milliseconds you would do it like so, making use of the Add method that takes a TimeSpan as a parameter.

var future = TimeOnly.FromDateTime(DateTime.Now)

To move in the other direction, that is to find out the time one hour, thirty minutes ago, use negative numbers as parameters to the Add methods.

Keep in mind that TimeOnly only stores the time, so this computation (four minutes before midnight) will wrap around and give you 23:56.

// Passing no arguments assumes you want to start at 0:00.00.000000
var newYearEve = new TimeOnly().AddMinutes(-4);

However, you might want to know when the day has wrapped.

There are overloaded Add methods that take out parameters where this information is stored.

So using our previous example:

var newYearEveWrapped = new TimeOnly().AddMinutes(-1, out var daysWrapped);

The daysWrapped variable here will contain -1, which will be the additional information that the returned TimeOnly is in fact a day ago.

This would be useful information for some computations involving time but have a date factor (for example late fees calculation).

Finally, the TimeOnly has a brilliant method that helps with determining the relationship between two dates.

The following code will print “Good morning” if you run it between midnight and noon; and something else anytime after that.

var midnight = new TimeOnly(0, 0);
var noon = new TimeOnly(12, 0);

if (now.IsBetween(midnight, noon))
    Console.WriteLine("Good morning");
    Console.WriteLine("Good afternoon/evening");

For anything more advanced, you can subtract two TimeOnly objects. The resulting object is a TimeSpan that you can interrogate.


This is an excellent type that will make time arithmetic much easier.

Personally I struggle with using the TimeSpan correctly to represent time for computations - it is not exactly intuitive to use the same construct for the dual purposes of a time period as well as an actual time.

The code is in my Github.


There is a companion TimeOnly type that is designed for use for dealing with time without a date component. It is much more intuitive to use than a TimeSpan

This is Day 3 of the 30 Days Of .NET 6 where every day I will attempt to explain one new / improved thing in the upcoming release of .NET 6.

Happy hacking!