Get Merged Cell Area with EPPLus

You can get all merged cells from worksheet, hence you can find the merged range a specific cell belongs to using the following:

 public string GetMergedRange(ExcelWorksheet worksheet, string cellAddress)
    {
        ExcelWorksheet.MergeCellsCollection mergedCells = worksheet.MergedCells;
        foreach (var merged in mergedCells)
        {
            ExcelRange range = worksheet.Cells[merged];
            ExcelCellAddress cell = new ExcelCellAddress(cellAddress);
            if (range.Start.Row<=cell.Row && range.Start.Column <= cell.Column)
            {
                if (range.End.Row >= cell.Row && range.End.Column >= cell.Column)
                {
                    return merged.ToString();
                }
            }
        }
        return "";
    }

Update:

Turns out that there is a much easier way using EPPLUS, just do the following:

var mergedadress = worksheet.MergedCells[row, column];

For example, if B1 is in a merged range "A1:C1":

 var mergedadress = worksheet.MergedCells[1, 2]; //value of mergedadress will be "A1:C1".

2 is the column number because B is the 2nd column.

This will provide you exact width of merged cells:

workSheet.Cells[workSheet.MergedCells[row, col]].Columns 

There is no such property out of the box but the worksheet has a MergedCells property with an array of all the merged cell addresses in the worksheet and a GetMergeCellId() method which will give you the index for a given cell address.

We can therefore combine these into a little extension method you can use to get the address. Something like this:

public static string GetMergedRangeAddress(this ExcelRange @this)
{
    if (@this.Merge)
    {
        var idx = @this.Worksheet.GetMergeCellId(@this.Start.Row, @this.Start.Column);
        return @this.Worksheet.MergedCells[idx-1]; //the array is 0-indexed but the mergeId is 1-indexed...
    }
    else
    {
        return @this.Address;
    }
}

which you can use as follows:

using (var excel = new ExcelPackage(new FileInfo("inputFile.xlsx")))
{
    var ws = excel.Workbook.Worksheets["sheet1"];
    var b3address = ws.Cells["B3"].GetMergedRangeAddress();

}

(Note that in the event that you use this method on a multi-celled range it will return the merged cell address for the first cell in the range only)