1. IronXL
2. How-Tos
3. Excel Add in C#

C# Excel Add-in (Code Example Tutorial)

ByChaknith Bin

July 19, 2020

Updated  June 1, 2025

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When developing applications, you need to be able to manage data without Excel spreadsheets but still communicate with the files. For example, you may need to insert new rows or columns in an existing Excel Spreadsheet programmatically. Using the functions for the umbrella concept "Excel: Add" in C#, we can add all these and more. See the examples below.

Step 1

1. Download the IronXL Excel Library

To access the functions to add rows and columns in Excel, first, we need to download the IronXL Excel Library. This is free for development in your project. Download the DLL directly or you can use the NuGet install method.

Install-Package IronXL.Excel

How to Tutorial

2. Excel Add Row in C#

Now that we have installed IronXL, it will be easy to insert new rows and columns in existing Excel Spreadsheets using C# programming.

First, access your Excel SpreadSheet and specify the WorkSheet where new rows or columns need to be added.

2.1. Add Row in Last Position

In our first example, we'll show how to add a new row in the last position.

Suppose that our Excel file is named sample.xlsx, and it has 5 columns from A to E. Using the following method, we can add a new row:

// Add a New Row in Last Position
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");
        // Calculate the position for the new row
        int i = ws.Rows.Count + 1;

        // Set values for each cell in the new row
        ws["A" + i].Value = "New Row";
        ws["B" + i].Value = "New Row";
        ws["C" + i].Value = "New Row";
        ws["D" + i].Value = "New Row";
        ws["E" + i].Value = "New Row";

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

// Add a New Row in Last Position
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");
        // Calculate the position for the new row
        int i = ws.Rows.Count + 1;

        // Set values for each cell in the new row
        ws["A" + i].Value = "New Row";
        ws["B" + i].Value = "New Row";
        ws["C" + i].Value = "New Row";
        ws["D" + i].Value = "New Row";
        ws["E" + i].Value = "New Row";

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

' Add a New Row in Last Position
Imports IronXL

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		' Load the existing Excel workbook
		Dim wb As WorkBook = WorkBook.Load("sample.xlsx")
		' Get the specific worksheet
		Dim ws As WorkSheet = wb.GetWorkSheet("Sheet1")
		' Calculate the position for the new row
		Dim i As Integer = ws.Rows.Count + 1

		' Set values for each cell in the new row
		ws("A" & i).Value = "New Row"
		ws("B" & i).Value = "New Row"
		ws("C" & i).Value = "New Row"
		ws("D" & i).Value = "New Row"
		ws("E" & i).Value = "New Row"

		' Save changes
		wb.SaveAs("sample.xlsx")
	End Sub
End Class

This will create a new row in the last position with the value New Row in the Excel Spreadsheet sample.xlsx.

2.2. Add Row in First Position

It is also very simple to add a new row in the first position of the Excel Spreadsheet.

For this purpose, firstly we need to move all existing rows down to make room at the top for the new row.

Here's the example on how to add a new row in the first position:

// Add a New Row in First Position
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");

        // Loop through the rows to shift them down
        for (int j = ws.Rows.Count; j >= 1; j--)
        {
            // Move each row down by one position
            ws["A" + (j + 1)].Value = ws["A" + j].Value;
            ws["B" + (j + 1)].Value = ws["B" + j].Value;
            ws["C" + (j + 1)].Value = ws["C" + j].Value;
            ws["D" + (j + 1)].Value = ws["D" + j].Value;
            ws["E" + (j + 1)].Value = ws["E" + j].Value;
        }

        // Add a new row at the first position
        ws["A1"].Value = "New First Row";
        ws["B1"].Value = "New First Row";
        ws["C1"].Value = "New First Row";
        ws["D1"].Value = "New First Row";
        ws["E1"].Value = "New First Row";

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

// Add a New Row in First Position
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");

        // Loop through the rows to shift them down
        for (int j = ws.Rows.Count; j >= 1; j--)
        {
            // Move each row down by one position
            ws["A" + (j + 1)].Value = ws["A" + j].Value;
            ws["B" + (j + 1)].Value = ws["B" + j].Value;
            ws["C" + (j + 1)].Value = ws["C" + j].Value;
            ws["D" + (j + 1)].Value = ws["D" + j].Value;
            ws["E" + (j + 1)].Value = ws["E" + j].Value;
        }

        // Add a new row at the first position
        ws["A1"].Value = "New First Row";
        ws["B1"].Value = "New First Row";
        ws["C1"].Value = "New First Row";
        ws["D1"].Value = "New First Row";
        ws["E1"].Value = "New First Row";

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

' Add a New Row in First Position
Imports IronXL

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		' Load the existing Excel workbook
		Dim wb As WorkBook = WorkBook.Load("sample.xlsx")
		' Get the specific worksheet
		Dim ws As WorkSheet = wb.GetWorkSheet("Sheet1")

		' Loop through the rows to shift them down
		For j As Integer = ws.Rows.Count To 1 Step -1
			' Move each row down by one position
			ws("A" & (j + 1)).Value = ws("A" & j).Value
			ws("B" & (j + 1)).Value = ws("B" & j).Value
			ws("C" & (j + 1)).Value = ws("C" & j).Value
			ws("D" & (j + 1)).Value = ws("D" & j).Value
			ws("E" & (j + 1)).Value = ws("E" & j).Value
		Next j

		' Add a new row at the first position
		ws("A1").Value = "New First Row"
		ws("B1").Value = "New First Row"
		ws("C1").Value = "New First Row"
		ws("D1").Value = "New First Row"
		ws("E1").Value = "New First Row"

		' Save changes
		wb.SaveAs("sample.xlsx")
	End Sub
End Class

Let's compare the changes done by the code in our sample.xlsx document.

Before	After

Here we can see that before, the sample.xlsx file had 10 rows. With the new row added in the first position, it now has 11 rows.

2.3. Add Row in First with Column Header

In cases where the first row includes column headers, you can start adding data from the second row and retain headers on row 0.

3. Excel Add Column in C#

It is also possible to add a new column to an existing Excel Spreadsheet in our C# project.

Suppose that we have 5 columns in our Excel Spreadsheet called sample.xlsx, ranging from A to E, and we want to add a new column in the first position, A. See the code sample below:

// Add a New Column
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");

        // Loop through each row to move existing columns to the right
        for (int i = 1; i <= ws.Rows.Count; i++)
        {
            ws["F" + i].Value = ws["E" + i].Value;
            ws["E" + i].Value = ws["D" + i].Value;
            ws["D" + i].Value = ws["C" + i].Value;
            ws["C" + i].Value = ws["B" + i].Value;
            ws["B" + i].Value = ws["A" + i].Value;
            ws["A" + i].Value = "New Column Added";
        }

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

// Add a New Column
using IronXL;

class Program
{
    static void Main(string[] args)
    {
        // Load the existing Excel workbook
        WorkBook wb = WorkBook.Load("sample.xlsx");
        // Get the specific worksheet
        WorkSheet ws = wb.GetWorkSheet("Sheet1");

        // Loop through each row to move existing columns to the right
        for (int i = 1; i <= ws.Rows.Count; i++)
        {
            ws["F" + i].Value = ws["E" + i].Value;
            ws["E" + i].Value = ws["D" + i].Value;
            ws["D" + i].Value = ws["C" + i].Value;
            ws["C" + i].Value = ws["B" + i].Value;
            ws["B" + i].Value = ws["A" + i].Value;
            ws["A" + i].Value = "New Column Added";
        }

        // Save changes
        wb.SaveAs("sample.xlsx");
    }
}

' Add a New Column
Imports IronXL

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		' Load the existing Excel workbook
		Dim wb As WorkBook = WorkBook.Load("sample.xlsx")
		' Get the specific worksheet
		Dim ws As WorkSheet = wb.GetWorkSheet("Sheet1")

		' Loop through each row to move existing columns to the right
		For i As Integer = 1 To ws.Rows.Count
			ws("F" & i).Value = ws("E" & i).Value
			ws("E" & i).Value = ws("D" & i).Value
			ws("D" & i).Value = ws("C" & i).Value
			ws("C" & i).Value = ws("B" & i).Value
			ws("B" & i).Value = ws("A" & i).Value
			ws("A" & i).Value = "New Column Added"
		Next i

		' Save changes
		wb.SaveAs("sample.xlsx")
	End Sub
End Class

Let's view the changes done by the code in sample.xlsx:

Before	After

We can see that a new column was added in first position A, and the rest were pushed back, resulting in a total of 6 columns from A to F.

Library Quick Access

Read the IronXL Documentation

Read the documentation for IronXL for more functions and information on adding rows, columns, and other Excel C# functionality.

Read the IronXL Documentation

Chaknith Bin

  Chat with engineering team now

Software Engineer

Chaknith works on IronXL and IronBarcode. He has deep expertise in C# and .NET, helping improve the software and support customers. His insights from user interactions contribute to better products, documentation, and overall experience.