How can I round up the time to the nearest X minutes?

Question

Is there a simple function for rounding UP a DateTime to the nearest 15 minutes?

E.g.

2011-08-11 16:59 becomes 2011-08-11 17:00

2011-08-11 17:00 stays as 2011-08-11 17:00

2011-08-11 17:01 becomes 2011-08-11 17:15

Answer 1

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime((dt.Ticks + d.Ticks - 1) / d.Ticks * d.Ticks, dt.Kind);
}

Example:

var dt1 = RoundUp(DateTime.Parse("2011-08-11 16:59"), TimeSpan.FromMinutes(15));
// dt1 == {11/08/2011 17:00:00}

var dt2 = RoundUp(DateTime.Parse("2011-08-11 17:00"), TimeSpan.FromMinutes(15));
// dt2 == {11/08/2011 17:00:00}

var dt3 = RoundUp(DateTime.Parse("2011-08-11 17:01"), TimeSpan.FromMinutes(15));
// dt3 == {11/08/2011 17:15:00}

Answer 2

Came up with a solution that doesn't involve multiplying and dividing long numbers.

public static DateTime RoundUp(this DateTime dt, TimeSpan d)
{
    var modTicks = dt.Ticks % d.Ticks;
    var delta = modTicks != 0 ? d.Ticks - modTicks : 0;
    return new DateTime(dt.Ticks + delta, dt.Kind);
}

public static DateTime RoundDown(this DateTime dt, TimeSpan d)
{
    var delta = dt.Ticks % d.Ticks;
    return new DateTime(dt.Ticks - delta, dt.Kind);
}

public static DateTime RoundToNearest(this DateTime dt, TimeSpan d)
{
    var delta = dt.Ticks % d.Ticks;
    bool roundUp = delta > d.Ticks / 2;
    var offset = roundUp ? d.Ticks : 0;

    return new DateTime(dt.Ticks + offset - delta, dt.Kind);
}

Usage:

var date = new DateTime(2010, 02, 05, 10, 35, 25, 450); // 2010/02/05 10:35:25
var roundedUp = date.RoundUp(TimeSpan.FromMinutes(15)); // 2010/02/05 10:45:00
var roundedDown = date.RoundDown(TimeSpan.FromMinutes(15)); // 2010/02/05 10:30:00
var roundedToNearest = date.RoundToNearest(TimeSpan.FromMinutes(15)); // 2010/02/05 10:30:00

Answer 3

if you need to round to a nearest time interval (not up) then i suggest to use the following

    static DateTime RoundToNearestInterval(DateTime dt, TimeSpan d)
    {
        int f=0;
        double m = (double)(dt.Ticks % d.Ticks) / d.Ticks;
        if (m >= 0.5)
            f=1;            
        return new DateTime(((dt.Ticks/ d.Ticks)+f) * d.Ticks);
    }

Answer 4

I've seen a nuber of useful implementations, like the one from @dtb or @redent84. Since the performance difference is negligible, I stayed away from bit shifts and simply created readable code. I often use these extensions in my utility libraries.

public static class DateTimeExtensions
{
    public static DateTime RoundToTicks(this DateTime target, long ticks) => new DateTime((target.Ticks + ticks / 2) / ticks * ticks, target.Kind);
    public static DateTime RoundUpToTicks(this DateTime target, long ticks) => new DateTime((target.Ticks + ticks - 1) / ticks * ticks, target.Kind);
    public static DateTime RoundDownToTicks(this DateTime target, long ticks) => new DateTime(target.Ticks / ticks * ticks, target.Kind);

    public static DateTime Round(this DateTime target, TimeSpan round) => RoundToTicks(target, round.Ticks);
    public static DateTime RoundUp(this DateTime target, TimeSpan round) => RoundUpToTicks(target, round.Ticks);
    public static DateTime RoundDown(this DateTime target, TimeSpan round) => RoundDownToTicks(target, round.Ticks);

    public static DateTime RoundToMinutes(this DateTime target, int minutes = 1) => RoundToTicks(target, minutes * TimeSpan.TicksPerMinute);
    public static DateTime RoundUpToMinutes(this DateTime target, int minutes = 1) => RoundUpToTicks(target, minutes * TimeSpan.TicksPerMinute);
    public static DateTime RoundDownToMinutes(this DateTime target, int minutes = 1) => RoundDownToTicks(target, minutes * TimeSpan.TicksPerMinute);

    public static DateTime RoundToHours(this DateTime target, int hours = 1) => RoundToTicks(target, hours * TimeSpan.TicksPerHour);
    public static DateTime RoundUpToHours(this DateTime target, int hours = 1) => RoundUpToTicks(target, hours * TimeSpan.TicksPerHour);
    public static DateTime RoundDownToHours(this DateTime target, int hours = 1) => RoundDownToTicks(target, hours * TimeSpan.TicksPerHour);

    public static DateTime RoundToDays(this DateTime target, int days = 1) => RoundToTicks(target, days * TimeSpan.TicksPerDay);
    public static DateTime RoundUpToDays(this DateTime target, int days = 1) => RoundUpToTicks(target, days * TimeSpan.TicksPerDay);
    public static DateTime RoundDownToDays(this DateTime target, int days = 1) => RoundDownToTicks(target, days * TimeSpan.TicksPerDay);
}

Answer 5

void Main()
{
    var date1 = new DateTime(2011, 8, 11, 16, 59, 00);
    date1.Round15().Dump();

    var date2 = new DateTime(2011, 8, 11, 17, 00, 02);
    date2.Round15().Dump();

    var date3 = new DateTime(2011, 8, 11, 17, 01, 23);
    date3.Round15().Dump();

    var date4 = new DateTime(2011, 8, 11, 17, 00, 00);
    date4.Round15().Dump();
}

public static class Extentions
{
    public static DateTime Round15(this DateTime value)
    {   
        var ticksIn15Mins = TimeSpan.FromMinutes(15).Ticks;

        return (value.Ticks % ticksIn15Mins == 0) ? value : new DateTime((value.Ticks / ticksIn15Mins + 1) * ticksIn15Mins);
    }
}

Results:

8/11/2011 5:00:00 PM
8/11/2011 5:15:00 PM
8/11/2011 5:15:00 PM
8/11/2011 5:00:00 PM

Answer 6

Since I hate reinventing the wheel, I'd probably follow this algorithm to round a DateTime value to a specified increment of time (Timespan):

• Convert the DateTime value to be rounded to a decimal floating-point value representing the whole and fractional number of TimeSpan units.
• Round that to an integer, using Math.Round().
• Scale back to ticks by multiplying the rounded integer by the number of ticks in the TimeSpan unit.
• Instantiate a new DateTime value from the rounded number of ticks and return it to the caller.

Here's the code:

public static class DateTimeExtensions
{

    public static DateTime Round( this DateTime value , TimeSpan unit )
    {
        return Round( value , unit , default(MidpointRounding) ) ;
    }

    public static DateTime Round( this DateTime value , TimeSpan unit , MidpointRounding style )
    {
        if ( unit <= TimeSpan.Zero ) throw new ArgumentOutOfRangeException("unit" , "value must be positive") ;

        Decimal  units        = (decimal) value.Ticks / (decimal) unit.Ticks ;
        Decimal  roundedUnits = Math.Round( units , style ) ;
        long     roundedTicks = (long) roundedUnits * unit.Ticks ;
        DateTime instance     = new DateTime( roundedTicks ) ;

        return instance ;
    }

}

Answer 7

My version

DateTime newDateTimeObject = oldDateTimeObject.AddMinutes(15 - oldDateTimeObject.Minute % 15);

As a method it would lock like this

public static DateTime GetNextQuarterHour(DateTime oldDateTimeObject)
{
    return oldDateTimeObject.AddMinutes(15 - oldDateTimeObject.Minute % 15);
}

and is called like that

DateTime thisIsNow = DateTime.Now;
DateTime nextQuarterHour = GetNextQuarterHour(thisIsNow);

Answer 8

Caution: the formula above is incorrect, i.e. the following:

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime(((dt.Ticks + d.Ticks - 1) / d.Ticks) * d.Ticks);
}

should be rewritten as:

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime(((dt.Ticks + d.Ticks/2) / d.Ticks) * d.Ticks);
}

Answer 9

A more verbose solution, that uses modulo and avoids unnecessary calculation.

public static class DateTimeExtensions
{
    public static DateTime RoundUp(this DateTime dt, TimeSpan ts)
    {
        return Round(dt, ts, true);
    }

    public static DateTime RoundDown(this DateTime dt, TimeSpan ts)
    {
        return Round(dt, ts, false);
    }

    private static DateTime Round(DateTime dt, TimeSpan ts, bool up)
    {
        var remainder = dt.Ticks % ts.Ticks;
        if (remainder == 0)
        {
            return dt;
        }

        long delta;
        if (up)
        {
            delta = ts.Ticks - remainder;
        }
        else
        {
            delta = -remainder;
        }

        return dt.AddTicks(delta);
    }
}

Answer 10

My DateTimeOffset version, based on Ramon's answer:

public static class DateExtensions
{
    public static DateTimeOffset RoundUp(this DateTimeOffset dt, TimeSpan d)
    {
        return new DateTimeOffset((dt.Ticks + d.Ticks - 1) / d.Ticks * d.Ticks, dt.Offset);
    }
}

Answer 11

This is a simple solution to round up to the nearest 1 minute. It preserves the TimeZone and Kind information of the DateTime. It can be modified to suit your own needs further (if you need to round to the nearest 5 minutes, etc).

DateTime dbNowExact = DateTime.Now;
DateTime dbNowRound1 = (dbNowExact.Millisecond == 0 ? dbNowExact : dbNowExact.AddMilliseconds(1000 - dbNowExact.Millisecond));
DateTime dbNowRound2 = (dbNowRound1.Second == 0 ? dbNowRound1 : dbNowRound1.AddSeconds(60 - dbNowRound1.Second));
DateTime dbNow = dbNowRound2;

Answer 12

You can use this method, it uses the specified date to ensure it maintains any of the globalization and datetime kind previously specified in the datetime object.

const long LNG_OneMinuteInTicks = 600000000;
/// <summary>
/// Round the datetime to the nearest minute
/// </summary>
/// <param name = "dateTime"></param>
/// <param name = "numberMinutes">The number minute use to round the time to</param>
/// <returns></returns>        
public static DateTime Round(DateTime dateTime, int numberMinutes = 1)
{
    long roundedMinutesInTicks = LNG_OneMinuteInTicks * numberMinutes;
    long remainderTicks = dateTime.Ticks % roundedMinutesInTicks;
    if (remainderTicks < roundedMinutesInTicks / 2)
    {
        // round down
        return dateTime.AddTicks(-remainderTicks);
    }

    // round up
    return dateTime.AddTicks(roundedMinutesInTicks - remainderTicks);
}

.Net Fiddle Test

If you want to use the TimeSpan to round, you can use this.

/// <summary>
/// Round the datetime
/// </summary>
/// <example>Round(dt, TimeSpan.FromMinutes(5)); => round the time to the nearest 5 minutes.</example>
/// <param name = "dateTime"></param>
/// <param name = "roundBy">The time use to round the time to</param>
/// <returns></returns>        
public static DateTime Round(DateTime dateTime, TimeSpan roundBy)
{            
    long remainderTicks = dateTime.Ticks % roundBy.Ticks;
    if (remainderTicks < roundBy.Ticks / 2)
    {
        // round down
        return dateTime.AddTicks(-remainderTicks);
    }

    // round up
    return dateTime.AddTicks(roundBy.Ticks - remainderTicks);
}

TimeSpan Fiddle

Answer 13

Solution from Ramon Smits with DateTime.MaxValue check:

DateTime RoundUp(DateTime dt, TimeSpan d) =>
    dt switch
    {
        var max when max.Equals(DateTime.MaxValue) => max,
        var v => new DateTime((v.Ticks + d.Ticks - 1) / d.Ticks * d.Ticks, v.Kind)
    };

Answer 14

You can try this:

string[] parts = ((DateTime)date_time.ToString("HH:mm:ss").Split(':');
int hr = Convert.ToInt32(parts[0]);
int mn = Convert.ToInt32(parts[1]);
int sec2min = (int)Math.Round(Convert.ToDouble(parts[2]) / 60.0, 0);

string adjTime = string.Format("1900-01-01 {0:00}:{1:00}:00.000",
(mn + sec2min > 59 ? (hr + 1 > 23 ? 0 : hr + 1) : hr),
 mn + sec2min > 59 ? 60 - mn + sec2min : mn + sec2min);

Each part (hr, min) must be incremented and adjusted to proper value for overflow, like 59 min > 00 then add 1 to hr, if it is 23, hr becomes 00. Ex. 07:34:57 is rounded to 07:35, 09:59:45 is rounded to 10:00, 23:59:45 is rounded to 00:00, which is the following day's time.

Answer 15

Elegant?

dt.AddSeconds(900 - (x.Minute * 60 + x.Second) % 900)