Take the 2-minute tour ×

I wonder how to compare two DateTime objects in .NET using DateTime methods Compare, CompareTo or Equals without comparing ticks.

I only need a tolerance level of milliseconds or seconds.

How can this be done?

share|improve this question
add comment

4 Answers

up vote 8 down vote accepted

You can subtract one DateTime from another to produce a TimeSpan that represents the time-difference between them. You can then test if the absolute value of this span is within your desired tolerance.

bool dtsWithinASecOfEachOther = d1.Subtract(d2).Duration() <= TimeSpan.FromSeconds(1);

The call to TimeSpan.Duration() can be omitted if you know that the first DateTime cannot represent an earlier point in time than the other, i.e. d1 >= d2.

To answer your query about the comparison methods, DateTime.Compare(d1, d2) produces the same result as d1.CompareTo(d2):

  • 0 if they represent the same point in time (d1.Equals(d2) , d1 == d2). Do note though, that the resolution of DateTime is 1 tick = 100 nanoseconds = 10 ^ -7 seconds.
  • A value greater than 0 if d1 is chronologically after d2 (d1 > d2)
  • A value less than 0 if d1 is chronologically before d2 (d1 < d2)
share|improve this answer
add comment

Use TimeSpan for your tolerance check - TimeSpan is the type returned from subtracting DateTimes:

TimeSpan tolerance = new TimeSpan(0,0,1);
return (date1 - date2) <= tolerance;

Compare, CompareTo and Equals will not take a tolerance for the comparison, so cannot used this way.

Other options are to create new DateTimes from the existing ones, discarding the unwanted accuracy and comparing the new ones:

DateTime noSeconds1 = new DateTime(d1.Year, d1.Month, d1.Day, d1.Hour, d1.Minute, 0);
DateTime noSeconds2 = new DateTime(d2.Year, d2.Month, d2.Day, d2.Hour, d2.Minute, 0);

DateTime.Compare(noSeconds1, noSeconds2);
share|improve this answer
add comment

Generally, if you want a single compare to tell you which date is less, equal to or greater, use DateTime.Compare(). Otherwise, you can use DateTime.Equals(). To add a tolerance value, subtract one from the other and compare result to be less than some TimeSpan:

// For seconds
if (laterDate-earlierDate<=TimeSpan.FromSeconds(1))

// For milliseconds
if (laterDate-earlierDate<=TimeSpan.FromMilliseconds(1))
share|improve this answer
add comment

You could convert both DateTimes to string and compare the resulting strings. Make sure you define the string format to avoid problems on machines with different regional settings than yours.

share|improve this answer
add comment

Your Answer


