Excel Writing in C# with EPPlus

Here we cover the basics of writing Excel files in C#. This can also be useful when you only read Excel files from 3rd parties, for example, for unit testing.

To write an Excel file using EPPlus in C#, we first need to create an instance of the ExcelPackage class.

using (var package = new ExcelPackage(new FileInfo(@"C:\temp\excel\myworkbook.xlsx")))
    // package work

Next, we can add a worksheet to our Excel package and write data to the cells in this worksheet:

using (var package = new ExcelPackage(new FileInfo(@"C:\temp\excel\myworkbook.xlsx")))
    var worksheet = package.Workbook.Worksheets.Add("Worksheet1");

    worksheet.Cells[1, 1].Value = "Hello";
    worksheet.Cells["B1"].Value = "world!";


Here are a few useful configuration options when writing to Excel files:

  • worksheet.Cells.AutoFitColumns() — Automatically fits the column width to the maximum length of the cell value in the column.
  • worksheet.Column(1).Width = 20 — Manually set the width of a column.

Unfortunately, unlike CSVHelper, EPPlus doesn't automatically convert Date/Time to the desired string format. You have to format the Date/Time values manually before writing to the Excel file. Here's how you can do it:

var dateTime = DateTime.Now;

worksheet.Cells[1, 1].Value = dateTime.ToString("MM/dd/yyyy");