Excel Number Format
using IronXL;
using System;
using System.Linq;

// Load an existing WorkSheet
WorkBook workBook = WorkBook.Load("sample.xls");
WorkSheet workSheet = workBook.WorkSheets.First();

// Set data display format to cell
// The cell value will look like 12300%
workSheet["A2"].Value = 123;
workSheet["A2"].FormatString = "0.0%";

// The cell value will look like 123.0000
workSheet["A2"].First().FormatString = "0.0000";

// Set data display format to range
DateTime dateValue = new DateTime(2020, 1, 1, 12, 12, 12);
workSheet["A3"].Value = dateValue;
workSheet["A4"].First().Value = new DateTime(2022, 3, 3, 10, 10, 10);
workSheet["A5"].First().Value = new DateTime(2021, 2, 2, 11, 11, 11);

var range = workSheet["A3:A5"];

// The cell(A3) value will look like 1/1/2020 12:12:12 PM
range.FormatString = "MM/dd/yy h:mm:ss";

workBook.SaveAs("numberFormats.xls");
NuGet Download
PM > Install-Package IronXL.Excel
Excel Number Format

Excel Number Format

We can use the FormatString property to format the display value of any Excel Cell or Range in C# with IronXL.

Using workSheet["A2"] will only select the Range of the specified address. To access a Cell, the First() method can be used. However, the FormatString property can be set directly from both Cell and Range. Therefore, the First() method can often be omitted. More Excel number formats can be applied using the same method as shown in the code example below.

How to use Excel NumberFormat in C#

  1. Download C# library to use Excel number format
  2. Load an existing Excel file with the Load method
  3. Set the FormatString property of a cell to specify the number format.
  4. Export the edited spreadsheet with the SaveAs method

In this code example, the IronXL library is used to manipulate Excel files. The WorkBook.Load method loads an existing Excel file, and the workSheet["A2"] syntax selects a specific cell within the worksheet to apply formatting. The FormatString property is then set to "0.00" to ensure that the cell value is displayed with two decimal places. Finally, workbook.SaveAs saves the modified workbook to a new file.

Learn to Set Excel Cell Data Formats with C#.
View on GitHub

Ready to Get Started?

Nuget Downloads 2,362,812Version:2026.11just released

Free NuGet Download
Total downloads: 2,362,812