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Posted 3 Mar 2009

Generate Excel files without using Microsoft Excel

, 22 Jun 2011
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A C# class to create Excel files without requiring Microsoft Excel.


Generating Excel files from web pages or other applications is a major subject in many articles. I'd like to present here a solution that does not require MS Excel to be installed on the target computer. This article shows how to create Microsoft Excel Binary Interchange File Format (BIFF) without using Microsoft Excel. BIFF is the native file format for Excel data, and can be viewed and modified in Microsoft Excel 97 or later.

Approaches and problems

The technique that is most frequently used to transfer data to an Excel workbooks is Automation. With Automation, you can call methods and properties that are specific to Excel tasks, but this solution has many drawbacks. Some of them are described in the Microsoft Knowledge Base. Additionally, you have to manage the lifetime of the temporary XLS files created on the server. Also, it is slow, because Excel runs in a separate process.

ExcelWriter class

The solution presented here is to write directly to a stream in Excel binary file format. For this purpose, I created very small C# class called ExcelWriter.

ExcelWriter class diagram
/// <summary>
/// Produces Excel file without using Excel
/// </summary>
public class ExcelWriter
    private Stream stream;
    private BinaryWriter writer;

    private ushort[] clBegin = { 0x0809, 8, 0, 0x10, 0, 0 };
    private ushort[] clEnd = { 0x0A, 00 };

    private void WriteUshortArray(ushort[] value)
        for (int i = 0; i < value.Length; i++)

    /// <summary>
    /// Initializes a new instance of the <see cref="ExcelWriter"/> class.
    /// </summary>
    /// <param name="stream">The stream.</param>
    public ExcelWriter(Stream stream)
    { = stream;
        writer = new BinaryWriter(stream);

    /// <summary>
    /// Writes the text cell value.
    /// </summary>
    /// <param name="row">The row.</param>
    /// <param name="col">The col.</param>
    /// <param name="value">The string value.</param>
    public void WriteCell(int row, int col, string value)
        ushort[] clData = { 0x0204, 0, 0, 0, 0, 0 };
        int iLen = value.Length;
        byte[] plainText = Encoding.ASCII.GetBytes(value);
        clData[1] = (ushort)(8 + iLen);
        clData[2] = (ushort)row;
        clData[3] = (ushort)col;
        clData[5] = (ushort)iLen;

    /// <summary>
    /// Writes the integer cell value.
    /// </summary>
    /// <param name="row">The row number.</param>
    /// <param name="col">The column number.</param>
    /// <param name="value">The value.</param>
    public void WriteCell(int row, int col, int value)
        ushort[] clData = { 0x027E, 10, 0, 0, 0 };
        clData[2] = (ushort)row;
        clData[3] = (ushort)col;
        int iValue = (value << 2) | 2;

    /// <summary>
    /// Writes the double cell value.
    /// </summary>
    /// <param name="row">The row number.</param>
    /// <param name="col">The column number.</param>
    /// <param name="value">The value.</param>
    public void WriteCell(int row, int col, double value)
        ushort[] clData = { 0x0203, 14, 0, 0, 0 };
        clData[2] = (ushort)row;
        clData[3] = (ushort)col;

    /// <summary>
    /// Writes the empty cell.
    /// </summary>
    /// <param name="row">The row number.</param>
    /// <param name="col">The column number.</param>
    public void WriteCell(int row, int col)
        ushort[] clData = { 0x0201, 6, 0, 0, 0x17 };
        clData[2] = (ushort)row;
        clData[3] = (ushort)col;

    /// <summary>
    /// Must be called once for creating XLS file header
    /// </summary>
    public void BeginWrite()

    /// <summary>
    /// Ends the writing operation, but do not close the stream
    /// </summary>
    public void EndWrite()

Using the code

The ExcelWriter sample is a console application that writes an XLS file to the name and location specified. The XLS file that is created is simply an empty spreadsheet. Then, you can start to write cell values by calling the WriteCell method with the row number, column number, and a cell value as parameters:

namespace XLSExportDemo
    class Program
        static void Main(string[] args)
            FileStream stream = new FileStream("demo.xls", FileMode.OpenOrCreate);
            ExcelWriter writer = new ExcelWriter(stream);
            writer.WriteCell(0, 0, "ExcelWriter Demo");
            writer.WriteCell(1, 0, "int");
            writer.WriteCell(1, 1, 10);
            writer.WriteCell(2, 0, "double");
            writer.WriteCell(2, 1, 1.5);
            writer.WriteCell(3, 0, "empty");
            writer.WriteCell(3, 1);

The picture below shows the final result of this sample:

The ExcelWriter class supports numeric and text values for the cells, and can be used for exporting data from the database to an XLS file, or for producing an XLS stream from a website on the fly.

I hope this article gives you a head start in working with Excel files from .NET and C#.


  • 03 March 2009 - Initial submission.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Serhiy Perevoznyk
Belgium Belgium
No Biography provided

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Comments and Discussions

GeneralRe: .NET library (open source) could be considered as alternative, has more and source code Pin
Serhiy Perevoznyk13-Nov-10 0:31
memberSerhiy Perevoznyk13-Nov-10 0:31 
GeneralSuggested change to code sample Pin
sdesciencelover9-Nov-10 4:30
membersdesciencelover9-Nov-10 4:30 
GeneralMy vote of 4 Pin
sdesciencelover9-Nov-10 4:26
membersdesciencelover9-Nov-10 4:26 
GeneralAdding Formulas Pin
twehr9-Nov-10 3:45
membertwehr9-Nov-10 3:45 
GeneralROCK STAR! Pin
Roger Ireland3-Nov-10 15:27
memberRoger Ireland3-Nov-10 15:27 
QuestionAdding simple formatting? Pin
Member 9171743-Nov-10 11:12
memberMember 9171743-Nov-10 11:12 
AnswerRe: Adding simple formatting? Pin
Serhiy Perevoznyk22-Jun-11 9:36
memberSerhiy Perevoznyk22-Jun-11 9:36 
GeneralHtml is also possible Pin
Tom Janssens2-Nov-10 21:44
memberTom Janssens2-Nov-10 21:44 
While this might be a nice lib, in the past I created simple HTML files containing a table, and I renamed the file extension to .XLS; this works as well, and is way simpler IMHO.

GeneralRe: Html is also possible Pin
Roger Ireland3-Nov-10 15:28
memberRoger Ireland3-Nov-10 15:28 
GeneralRe: Html is also possible Pin
Tom Janssens4-Nov-10 7:14
memberTom Janssens4-Nov-10 7:14 
GeneralVery Good! Pin
xzz01952-Nov-10 2:42
memberxzz01952-Nov-10 2:42 
Generalnice articles Pin
RyanALEX16-Aug-10 19:01
memberRyanALEX16-Aug-10 19:01 
Questioncreate cell with font size and bold Pin
Member 254080414-May-10 12:33
memberMember 254080414-May-10 12:33 
AnswerRe: create cell with font size and bold Pin
Serhiy Perevoznyk22-Jun-11 9:37
memberSerhiy Perevoznyk22-Jun-11 9:37 
GeneralThank You Pin
kartp2-Apr-10 21:35
memberkartp2-Apr-10 21:35 
GeneralSet the width of the Columns of the Excel file Pin
Dazheng Xu11-Mar-10 11:42
memberDazheng Xu11-Mar-10 11:42 
GeneralRe: Set the width of the Columns of the Excel file Pin
Serhiy Perevoznyk22-Jun-11 9:38
memberSerhiy Perevoznyk22-Jun-11 9:38 
QuestionHow to write excel with exporting data from ms word doc table? Pin
ssuriyani223-Dec-09 15:09
memberssuriyani223-Dec-09 15:09 
GeneralMicrosoft Excel 2.1 Worksheet format Pin
edgar_v_reyes28-Nov-09 7:52
memberedgar_v_reyes28-Nov-09 7:52 
GeneralRe: Microsoft Excel 2.1 Worksheet format Pin
Serhiy Perevoznyk28-Nov-09 22:33
memberSerhiy Perevoznyk28-Nov-09 22:33 
GeneralCell limitation to 255 chars Pin
eddy mulyono28-Oct-09 18:12
membereddy mulyono28-Oct-09 18:12 
GeneralDutch characters break the document Pin
D.Janjicek10-Aug-09 20:40
memberD.Janjicek10-Aug-09 20:40 
GeneralRe: Dutch characters break the document Pin
DanielLey9-Oct-09 3:06
memberDanielLey9-Oct-09 3:06 
GeneralRe: Dutch characters break the document Pin
Member 30944881-Jan-10 21:57
memberMember 30944881-Jan-10 21:57 
QuestionRe: Dutch characters break the document Pin
Tropics2a21-Apr-10 2:14
memberTropics2a21-Apr-10 2:14 

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