In C#, how can I calculate the number of business (or weekdays) days between two dates?
37 Answers
Well this has been beaten to death. :) However I'm still going to provide another answer because I needed something a bit different. This solution is different in that it returns a Business TimeSpan between the start and end, and you can set the business hours of the day, and add holidays. So you can use it to calculate if it happens within a day, across days, over weekends, and even holidays. And you can get just the business days or not by just getting what you need from the returned TimeSpan object. And the way it uses lists of days, you can see how very easy it would be to add the list of non-work days if it's not the typical Sat and Sun. And I tested for a year, and it seems super fast.
I just hope the pasting of the code is accurate. But I know it works.
public static TimeSpan GetBusinessTimespanBetween(
DateTime start, DateTime end,
TimeSpan workdayStartTime, TimeSpan workdayEndTime,
List<DateTime> holidays = null)
{
if (end < start)
throw new ArgumentException("start datetime must be before end datetime.");
// Just create an empty list for easier coding.
if (holidays == null) holidays = new List<DateTime>();
if (holidays.Where(x => x.TimeOfDay.Ticks > 0).Any())
throw new ArgumentException("holidays can not have a TimeOfDay, only the Date.");
var nonWorkDays = new List<DayOfWeek>() { DayOfWeek.Saturday, DayOfWeek.Sunday };
var startTime = start.TimeOfDay;
// If the start time is before the starting hours, set it to the starting hour.
if (startTime < workdayStartTime) startTime = workdayStartTime;
var timeBeforeEndOfWorkDay = workdayEndTime - startTime;
// If it's after the end of the day, then this time lapse doesn't count.
if (timeBeforeEndOfWorkDay.TotalSeconds < 0) timeBeforeEndOfWorkDay = new TimeSpan();
// If start is during a non work day, it doesn't count.
if (nonWorkDays.Contains(start.DayOfWeek)) timeBeforeEndOfWorkDay = new TimeSpan();
else if (holidays.Contains(start.Date)) timeBeforeEndOfWorkDay = new TimeSpan();
var endTime = end.TimeOfDay;
// If the end time is after the ending hours, set it to the ending hour.
if (endTime > workdayEndTime) endTime = workdayEndTime;
var timeAfterStartOfWorkDay = endTime - workdayStartTime;
// If it's before the start of the day, then this time lapse doesn't count.
if (timeAfterStartOfWorkDay.TotalSeconds < 0) timeAfterStartOfWorkDay = new TimeSpan();
// If end is during a non work day, it doesn't count.
if (nonWorkDays.Contains(end.DayOfWeek)) timeAfterStartOfWorkDay = new TimeSpan();
else if (holidays.Contains(end.Date)) timeAfterStartOfWorkDay = new TimeSpan();
// Easy scenario if the times are during the day day.
if (start.Date.CompareTo(end.Date) == 0)
{
if (nonWorkDays.Contains(start.DayOfWeek)) return new TimeSpan();
else if (holidays.Contains(start.Date)) return new TimeSpan();
return endTime - startTime;
}
else
{
var timeBetween = end - start;
var daysBetween = (int)Math.Floor(timeBetween.TotalDays);
var dailyWorkSeconds = (int)Math.Floor((workdayEndTime - workdayStartTime).TotalSeconds);
var businessDaysBetween = 0;
// Now the fun begins with calculating the actual Business days.
if (daysBetween > 0)
{
var nextStartDay = start.AddDays(1).Date;
var dayBeforeEnd = end.AddDays(-1).Date;
for (DateTime d = nextStartDay; d <= dayBeforeEnd; d = d.AddDays(1))
{
if (nonWorkDays.Contains(d.DayOfWeek)) continue;
else if (holidays.Contains(d.Date)) continue;
businessDaysBetween++;
}
}
var dailyWorkSecondsToAdd = dailyWorkSeconds * businessDaysBetween;
var output = timeBeforeEndOfWorkDay + timeAfterStartOfWorkDay;
output = output + new TimeSpan(0, 0, dailyWorkSecondsToAdd);
return output;
}
}
And here is test code: Note that you just have to put this function in a class called DateHelper for the test code to work.
[TestMethod]
public void TestGetBusinessTimespanBetween()
{
var workdayStart = new TimeSpan(8, 0, 0);
var workdayEnd = new TimeSpan(17, 0, 0);
var holidays = new List<DateTime>()
{
new DateTime(2018, 1, 15), // a Monday
new DateTime(2018, 2, 15) // a Thursday
};
var testdata = new[]
{
new
{
expectedMinutes = 0,
start = new DateTime(2016, 10, 19, 9, 50, 0),
end = new DateTime(2016, 10, 19, 9, 50, 0)
},
new
{
expectedMinutes = 10,
start = new DateTime(2016, 10, 19, 9, 50, 0),
end = new DateTime(2016, 10, 19, 10, 0, 0)
},
new
{
expectedMinutes = 5,
start = new DateTime(2016, 10, 19, 7, 50, 0),
end = new DateTime(2016, 10, 19, 8, 5, 0)
},
new
{
expectedMinutes = 5,
start = new DateTime(2016, 10, 19, 16, 55, 0),
end = new DateTime(2016, 10, 19, 17, 5, 0)
},
new
{
expectedMinutes = 15,
start = new DateTime(2016, 10, 19, 16, 50, 0),
end = new DateTime(2016, 10, 20, 8, 5, 0)
},
new
{
expectedMinutes = 10,
start = new DateTime(2016, 10, 19, 16, 50, 0),
end = new DateTime(2016, 10, 20, 7, 55, 0)
},
new
{
expectedMinutes = 5,
start = new DateTime(2016, 10, 19, 17, 10, 0),
end = new DateTime(2016, 10, 20, 8, 5, 0)
},
new
{
expectedMinutes = 0,
start = new DateTime(2016, 10, 19, 17, 10, 0),
end = new DateTime(2016, 10, 20, 7, 5, 0)
},
new
{
expectedMinutes = 545,
start = new DateTime(2016, 10, 19, 12, 10, 0),
end = new DateTime(2016, 10, 20, 12, 15, 0)
},
// Spanning multiple weekdays
new
{
expectedMinutes = 835,
start = new DateTime(2016, 10, 19, 12, 10, 0),
end = new DateTime(2016, 10, 21, 8, 5, 0)
},
// Spanning multiple weekdays
new
{
expectedMinutes = 1375,
start = new DateTime(2016, 10, 18, 12, 10, 0),
end = new DateTime(2016, 10, 21, 8, 5, 0)
},
// Spanning from a Thursday to a Tuesday, 5 mins short of complete day.
new
{
expectedMinutes = 1615,
start = new DateTime(2016, 10, 20, 12, 10, 0),
end = new DateTime(2016, 10, 25, 12, 5, 0)
},
// Spanning from a Thursday to a Tuesday, 5 mins beyond complete day.
new
{
expectedMinutes = 1625,
start = new DateTime(2016, 10, 20, 12, 10, 0),
end = new DateTime(2016, 10, 25, 12, 15, 0)
},
// Spanning from a Friday to a Monday, 5 mins beyond complete day.
new
{
expectedMinutes = 545,
start = new DateTime(2016, 10, 21, 12, 10, 0),
end = new DateTime(2016, 10, 24, 12, 15, 0)
},
// Spanning from a Friday to a Monday, 5 mins short complete day.
new
{
expectedMinutes = 535,
start = new DateTime(2016, 10, 21, 12, 10, 0),
end = new DateTime(2016, 10, 24, 12, 5, 0)
},
// Spanning from a Saturday to a Monday, 5 mins short complete day.
new
{
expectedMinutes = 245,
start = new DateTime(2016, 10, 22, 12, 10, 0),
end = new DateTime(2016, 10, 24, 12, 5, 0)
},
// Spanning from a Saturday to a Sunday, 5 mins beyond complete day.
new
{
expectedMinutes = 0,
start = new DateTime(2016, 10, 22, 12, 10, 0),
end = new DateTime(2016, 10, 23, 12, 15, 0)
},
// Times within the same Saturday.
new
{
expectedMinutes = 0,
start = new DateTime(2016, 10, 22, 12, 10, 0),
end = new DateTime(2016, 10, 23, 12, 15, 0)
},
// Spanning from a Saturday to the Sunday next week.
new
{
expectedMinutes = 2700,
start = new DateTime(2016, 10, 22, 12, 10, 0),
end = new DateTime(2016, 10, 30, 12, 15, 0)
},
// Spanning a year.
new
{
expectedMinutes = 143355,
start = new DateTime(2016, 10, 22, 12, 10, 0),
end = new DateTime(2017, 10, 30, 12, 15, 0)
},
// Spanning a year with 2 holidays.
new
{
expectedMinutes = 142815,
start = new DateTime(2017, 10, 22, 12, 10, 0),
end = new DateTime(2018, 10, 30, 12, 15, 0)
},
};
foreach (var item in testdata)
{
Assert.AreEqual(item.expectedMinutes,
DateHelper.GetBusinessTimespanBetween(
item.start, item.end,
workdayStart, workdayEnd,
holidays)
.TotalMinutes);
}
}
Works and without loops
This method doesn't use any loops and is actually quite simple. It expands the date range to full weeks since we know that each week has 5 business days. It then uses a lookup table to find the number of business days to subtract from the start and end to get the right result. I've expanded out the calculation to help show what's going on, but the whole thing could be condensed into a single line if needed.
Anyway, this works for me and so I thought I'd post it here in case it might help others. Happy coding.
Calculation
- t : Total number of days between dates (1 if min = max)
- a + b : Extra days needed to expand total to full weeks
- k : 1.4 is number of weekdays per week, i.e., (t / 7) * 5
- c : Number of weekdays to subtract from the total
- m : A lookup table used to find the value of "c" for each day of the week
Culture
Code assumes a Monday to Friday work week. For other cultures, such as Sunday to Thursday, you'll need to offset the dates prior to calculation.
Method
public int Weekdays(DateTime min, DateTime max)
{
if (min.Date > max.Date) throw new Exception("Invalid date span");
var t = (max.AddDays(1).Date - min.Date).TotalDays;
var a = (int) min.DayOfWeek;
var b = 6 - (int) max.DayOfWeek;
var k = 1.4;
var m = new int[]{0, 0, 1, 2, 3, 4, 5};
var c = m[a] + m[b];
return (int)((t + a + b) / k) - c;
}
This method returns the number of business days between two dates:
Here I use the DayOfWeek enum for checking weekends.
private static int BusinessDaysLeft(DateTime first, DateTime last)
{
var count = 0;
while (first.Date != last.Date)
{
if(first.DayOfWeek != DayOfWeek.Saturday && first.DayOfWeek != DayOfWeek.Sunday)
count++;
first = first.AddDays(1);
}
return count;
}
By using marinjw library, And solution provided by Alec Pojidaev i created below, this will skip public (you need to specify country) holidays:
Please Note that if you use actual DateTime and have hours present then you have to add .Date and best to reformat FromDate and ToDate as FromDate = FromDate.Date and ToDate = ToDate.Date
public static int GetProcessingTime(this DateTime? FromDate, DateTime? ToDate)
{
if (FromDate == null) return 0;
if (ToDate == null) return 0;
List<DateTime> Holidays = new List<DateTime>();
int startyear = FromDate.Value.Year;
int endyear = ToDate.Value.Year;
//loop years to extract all holidays
for(int i = startyear; i <= endyear; i++)
{
IList<DateTime> Temp = new PolandPublicHoliday().PublicHolidays(i);
Holidays.AddRange(Temp.ToList());
}
//exclude holidays outside of range
Holidays = Holidays.Where(x => x >= FromDate && x <= ToDate).ToList();
//exclude holidays that are set to be on sunday/saturday
Holidays = Holidays.Where(x => x.DayOfWeek != DayOfWeek.Sunday && x.DayOfWeek != DayOfWeek.Saturday).ToList();
//calculate date difference without sundays and saturdays Value need to be added as I am using nullable DateTime
double calcBusinessDays = 1 + ((FromDate.Value - ToDate.Value).TotalDays * 5 - (FromDate.Value.DayOfWeek - ToDate.Value.DayOfWeek) * 2) / 7;
if (FromDate.Value.DayOfWeek == DayOfWeek.Saturday) calcBusinessDays--;
if (ToDate.Value.DayOfWeek == DayOfWeek.Sunday) calcBusinessDays--;
//remove left holidays
if (Holidays!=null)
calcBusinessDays -= Holidays.Count;
return (int)calcBusinessDays;
}
I was having trouble finding a solid TSQL version of this code. Below is essentially a conversion of the C# code here with addition of the Holiday table which should be used to pre-calculate holidays.
CREATE TABLE dbo.Holiday
(
HolidayDt DATE NOT NULL,
Name NVARCHAR(50) NOT NULL,
IsWeekday BIT NOT NULL,
CONSTRAINT PK_Holiday PRIMARY KEY (HolidayDt)
)
GO
CREATE INDEX IDX_Holiday ON Holiday (HolidayDt, IsWeekday)
GO
CREATE function dbo.GetBusinessDays
(
@FirstDay datetime,
@LastDay datetime
)
RETURNS INT
AS
BEGIN
DECLARE @BusinessDays INT, @FullWeekCount INT
SELECT @FirstDay = CONVERT(DATETIME,CONVERT(DATE,@FirstDay))
, @LastDay = CONVERT(DATETIME,CONVERT(DATE,@LastDay))
IF @FirstDay > @LastDay
RETURN NULL;
SELECT @BusinessDays = DATEDIFF(DAY, @FirstDay, @LastDay) + 1
SELECT @FullWeekCount = @BusinessDays / 7;
-- find out if there are weekends during the time exceedng the full weeks
IF @BusinessDays > (@FullWeekCount * 7)
BEGIN
-- we are here to find out if there is a 1-day or 2-days weekend
-- in the time interval remaining after subtracting the complete weeks
DECLARE @firstDayOfWeek INT, @lastDayOfWeek INT;
SELECT @firstDayOfWeek = DATEPART(DW, @FirstDay), @lastDayOfWeek = DATEPART(DW, @LastDay);
IF @lastDayOfWeek < @firstDayOfWeek
SELECT @lastDayOfWeek = @lastDayOfWeek + 7;
IF @firstDayOfWeek <= 6
BEGIN
IF (@lastDayOfWeek >= 7) --Both Saturday and Sunday are in the remaining time interval
BEGIN
SELECT @BusinessDays = @BusinessDays - 2
END
ELSE IF @lastDayOfWeek>=6 --Only Saturday is in the remaining time interval
BEGIN
SELECT @BusinessDays = @BusinessDays - 1
END
END
ELSE IF @firstDayOfWeek <= 7 AND @lastDayOfWeek >=7 -- Only Sunday is in the remaining time interval
BEGIN
SELECT @BusinessDays = @BusinessDays - 1
END
END
-- subtract the weekends during the full weeks in the interval
DECLARE @Holidays INT;
SELECT @Holidays = COUNT(*)
FROM Holiday
WHERE HolidayDt BETWEEN @FirstDay AND @LastDay
AND IsWeekday = CAST(1 AS BIT)
SELECT @BusinessDays = @BusinessDays - (@FullWeekCount + @FullWeekCount) -- - @Holidays
RETURN @BusinessDays
END
Here is an approach if you are using MVC. I have also calculated national holidays or any festive days to be excluded by fetching it from holidayscalendar which you will need to make one.
foreach (DateTime day in EachDay(model))
{
bool key = false;
foreach (LeaveModel ln in holidaycalendar)
{
if (day.Date == ln.Date && day.DayOfWeek != DayOfWeek.Saturday && day.DayOfWeek != DayOfWeek.Sunday)
{
key = true; break;
}
}
if (day.DayOfWeek == DayOfWeek.Saturday || day.DayOfWeek == DayOfWeek.Sunday)
{
key = true;
}
if (key != true)
{
leavecount++;
}
}
Leavemodel is a list here
Here is an helper function I wrote for that task.
it also returns the count of weekends via the out parameter.
if you wish you can customize the "weekend" days in run time for countries that use different weekend days or to include holidays trough the weekendDays[] optional parameter :
public static int GetNetworkDays(DateTime startDate, DateTime endDate,out int totalWeekenDays, DayOfWeek[] weekendDays = null)
{
if (startDate >= endDate)
{
throw new Exception("start date can not be greater then or equel to end date");
}
DayOfWeek[] weekends = new DayOfWeek[] { DayOfWeek.Sunday, DayOfWeek.Saturday };
if (weekendDays != null)
{
weekends = weekendDays;
}
var totaldays = (endDate - startDate).TotalDays + 1; // add one to include the first day to
var counter = 0;
var workdaysCounter = 0;
var weekendsCounter = 0;
for (int i = 0; i < totaldays; i++)
{
if (weekends.Contains(startDate.AddDays(counter).DayOfWeek))
{
weekendsCounter++;
}
else
{
workdaysCounter++;
}
counter++;
}
totalWeekenDays = weekendsCounter;
return workdaysCounter;
}
I came up with the following solution
var dateStart = new DateTime(2019,01,10);
var dateEnd = new DateTime(2019,01,31);
var timeBetween = (dateEnd - dateStart).TotalDays + 1;
int numberOf7DayWeeks = (int)(timeBetween / 7);
int numberOfWeekendDays = numberOf7DayWeeks * 2;
int workingDays =(int)( timeBetween - numberOfWeekendDays);
if(dateStart.DayOfWeek == DayOfWeek.Saturday || dateEnd.DayOfWeek == DayOfWeek.Sunday){
workingDays -=2;
}
if(dateStart.DayOfWeek == DayOfWeek.Sunday || dateEnd.DayOfWeek == DayOfWeek.Saturday){
workingDays -=1;
}
You just have to iterate through each day in the time range and subtract a day from the counter if its a Saturday or a Sunday.
private float SubtractWeekend(DateTime start, DateTime end) {
float totaldays = (end.Date - start.Date).Days;
var iterationVal = totalDays;
for (int i = 0; i <= iterationVal; i++) {
int dayVal = (int)start.Date.AddDays(i).DayOfWeek;
if(dayVal == 6 || dayVal == 0) {
// saturday or sunday
totalDays--;
}
}
return totalDays;
}
Yet another approach for calculating business days, not considering holidays, but taking into account the time of day returning a fractional amount of days:
public static double GetBusinessDays(DateTime startD, DateTime endD)
{
while (IsWeekend(startD))
startD = startD.Date.AddDays(1);
while (IsWeekend(endD))
endD = endD.Date.AddDays(-1);
var bussDays = (endD - startD).TotalDays -
(2 * ((int)(endD - startD).TotalDays / 7)) -
(startD.DayOfWeek > endD.DayOfWeek ? 2 : 0);
return bussDays;
}
public static bool IsWeekend(DateTime d)
{
return d.DayOfWeek == DayOfWeek.Saturday || d.DayOfWeek == DayOfWeek.Sunday;
}
You can fiddle with it here: https://rextester.com/ASHRS53997
public static int CalculateBusinessDaysInRange(this DateTime startDate, DateTime endDate, params DateTime[] holidayDates)
{
endDate = endDate.Date;
if(startDate > endDate)
throw new ArgumentException("The end date can not be before the start date!", nameof(endDate));
int accumulator = 0;
DateTime itterator = startDate.Date;
do
{
if(itterator.DayOfWeek != DayOfWeek.Saturday && itterator.DayOfWeek != DayOfWeek.Sunday && !holidayDates.Any(hol => hol.Date == itterator))
{ accumulator++; }
}
while((itterator = itterator.AddDays(1)).Date <= endDate);
return accumulator
}
I'm only posting this because despite all of the excellent answers that have been given, none of the math made sense to me. This is definitely a KISS method that should work and be fairly maintainable. Granted if you are calculating ranges that are greater than 2-3 months this will not be the most effective way. We simply determine if it is a Saturday or Sunday or the date is a given holiday date. If it's not we add a business day. If it is then everything is fine.
I'm sure this could be even more so simplified with LINQ, but this way is much easier to understand.
Here's another example you can choose the weekend dates as well,
public int GetBuisnessDays(DateTime StartDate, DateTime EndDate)
{
int counter = 0;
if (StartDate.Date == EndDate.Date)
{
if (StartDate.DayOfWeek != DayOfWeek.Saturday && StartDate.DayOfWeek != DayOfWeek.Friday)
return 1;
return 0;
}
while (StartDate <= EndDate)
{
if (StartDate.DayOfWeek != DayOfWeek.Saturday && StartDate.DayOfWeek != DayOfWeek.Friday)
++counter;
StartDate = StartDate.AddDays(1);
}
return counter;
}
So I had a similar task except I had to calculate business days left (from date should not be more than to date), and end date should skip to next business day.
To make it more understandable/readable, I did this in the following steps
Updated toDate to the next business day if it is on weekend.
Find out the number of complete weeks between dates, and for each complete week consider 5 days in running total.
Now days left are only different of from and to weekdays (it won't be more than 6 days), so wrote a small loop to get it (skip Saturday and Sunday)
public static int GetBusinessDaysLeft(DateTime fromDate, DateTime toDate) { //Validate that startDate should be less than endDate if (fromDate >= toDate) return 0; //Move end date to Monday if on weekends if (toDate.DayOfWeek == DayOfWeek.Saturday || toDate.DayOfWeek == DayOfWeek.Sunday) while (toDate.DayOfWeek != DayOfWeek.Monday) toDate = toDate.AddDays(+1); //Consider 5 days per complete week in between start and end dates int remainder, quotient = Math.DivRem((toDate - fromDate).Days, 7, out remainder); var daysDiff = quotient * 5; var curDay = fromDate; while (curDay.DayOfWeek != toDate.DayOfWeek) { curDay = curDay.AddDays(1); if (curDay.DayOfWeek == DayOfWeek.Saturday || curDay.DayOfWeek == DayOfWeek.Sunday) continue; daysDiff += 1; } return daysDiff; }
Many of the answers are great but they don't take into account the start/end time. Here is my improved solutions (in C#) based on this answers but taking into account the start and end time. For example:
Monday 8/2/2021 to Wednesday 8/4/2021 is 2 days - In this case, 8/4/2021 is excluded because the time is not specified and in .Net it automatically assigned to 12:00 AM.
Monday 8/2/2021 12 PM to Wednesday 8/4/2021 12 PM is 2 days.
Friday 8/6/2021 12 PM to Tuesday 8/10/2021 6 PM is 2.25 days.
public static double GetWorkingDays(DateTime startDate, DateTime endDate) { // Get next full day from start date and last full day of end date var nextFullStartDate = startDate.AddDays(1).Date; var lastFullEndDate = endDate.Date; // Calculate total days based on start and end's day of week var dayOfWeekFactor = (nextFullStartDate.DayOfWeek - lastFullEndDate.DayOfWeek) * 2; if (lastFullEndDate.DayOfWeek == DayOfWeek.Sunday) { // In .net, day of week for Sunday is 0, we need to change it to 7 dayOfWeekFactor = ((int)nextFullStartDate.DayOfWeek - 7) * 2; } // Calculate working days (ie: Monday, Tuesday, Wednesday, Thursday and Friday) var workingDayCount = ((lastFullEndDate - nextFullStartDate).TotalDays * 5 - dayOfWeekFactor) / 7; // Subtract working days if full start date or last full end date is Sunday // Saturday is not included here because if startDate is Saturday the formula above would have excluded Saturday. If the endDate is Saturday, it would have been excluded too because the time would be Saturday 12:00 AM if (nextFullStartDate.DayOfWeek == DayOfWeek.Sunday || lastFullEndDate.DayOfWeek == DayOfWeek.Sunday) { workingDayCount--; } // Count the real start/end date if (startDate.DayOfWeek != DayOfWeek.Saturday && startDate.DayOfWeek != DayOfWeek.Sunday) { var startDateFraction = (nextFullStartDate - startDate).TotalHours / 24; workingDayCount += startDateFraction; } if (endDate.DayOfWeek != DayOfWeek.Saturday && endDate.DayOfWeek != DayOfWeek.Sunday) { var endDateFraction = (endDate - lastFullEndDate).TotalHours / 24; workingDayCount += endDateFraction; } return workingDayCount; }
Check this 1. https://github.com/yatishbalaji/moment-working-days#readme 2. https://www.npmjs.com/package/moment-working-days
It allows you to calculate working days, considering sequence of date(s). You can customize the week off days, and also declare custom dates for holidays (eg: public holidays) to exclude them from being counted as working day(s)
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