Exporting an excel file as to PDF file

pavan-edu · September 8, 2025, 5:30am

We are facing an export an excel file content to the PDF file, which is taking longer period in processing. what are the constraint need to considered for downloading a file of PDF from an excel file

Professionalize.Discourse · September 8, 2025, 5:30am

@pavan-edu

Exporting Excel to PDF with Aspose.Cells for .NET – Performance Tips

Below is a quick checklist and a sample code snippet that will help you minimise the conversion time when saving an XLSX/XLS workbook as a PDF file.

Common factors that affect conversion speed

Factor	Why it matters	How to mitigate
Workbook size – number of worksheets, rows, columns	More cells → more data to render	• Remove unused worksheets. • Delete empty rows/columns (`Worksheet.Cells.DeleteBlankRows();`).
Formulas & calculation engine	Each formula is evaluated before rendering	• Set `Workbook.Settings.CalcEngineEnabled = false;` (if you do not need up‑to‑date results). • Or call `Workbook.CalculateFormula()` once and then disable further calculation.
Charts, Images, Shapes	Each graphic is rasterised during PDF generation	• Delete unnecessary objects. • Reduce image resolution (`PdfSaveOptions.ImageResolution`).
PageSetup (margins, scaling, fit‑to‑page)	Complex page settings require extra layout work	• Use simple page settings (`Worksheet.PageSetup.FitToPagesWide = 1;` etc.).
Font handling	Embedding many fonts increases processing	• Use system fonts only, or set `PdfSaveOptions.EmbedStandardFonts = true;`.
Memory‑optimisation mode	Large files may trigger full in‑memory rendering	• Enable `PdfSaveOptions.OptimizeMemory = true;` (streaming mode).
Compression / Image quality	High‑quality images take longer to encode	• Choose a compression type (`PdfCompressionType.Jpeg`) and set a lower `ImageQuality` if acceptable.

Recommended PdfSaveOptions for faster conversion

using Aspose.Cells;
using Aspose.Cells.Rendering;

// Load the workbook (you can also use LoadOptions to skip calculation)
Workbook wb = new Workbook(@"C:\Input\largeFile.xlsx");

// OPTIONAL: If you do not need any formula recalculation
wb.Settings.CalcEngineEnabled = false;   // disables automatic calculation

// Simplify page setup (example: fit all columns on one page)
foreach (var sheet in wb.Worksheets)
{
    sheet.PageSetup.FitToPagesWide = 1;
    sheet.PageSetup.FitToPagesTall = 0; // unlimited height
}

// Configure PDF save options for speed
PdfSaveOptions pdfOpts = new PdfSaveOptions
{
    // Stream the output instead of loading everything in memory
    OptimizeMemory = true,

    // Reduce image resolution/quality if high fidelity is not required
    ImageResolution = 96,                // DPI (default is 150)
    ImageQuality = 80,                    // 0‑100 (lower = faster)

    // Choose a fast compression algorithm
    Compression = PdfCompressionType.Jpeg,

    // Embed only standard fonts (avoid embedding custom fonts)
    EmbedStandardFonts = true,

    // Disable writing of hidden worksheets (if any)
    SaveHiddenSheets = false,

    // Render only the first page for testing (remove for full export)
    // PageCount = 1
};

wb.Save(@"C:\Output\result.pdf", SaveFormat.Pdf, pdfOpts);

Key points in the example

OptimizeMemory = true forces Aspose.Cells to write the PDF page‑by‑page, greatly reducing RAM usage and often speeding up large conversions.
Lowering ImageResolution and ImageQuality cuts the time spent encoding raster graphics.
Disabling automatic calculation (CalcEngineEnabled = false) skips the formula engine entirely.
Simple FitToPagesWide page setup reduces layout complexity.

Additional Tips

Tip	How to apply
Use the latest Aspose.Cells version	Performance improvements are added in each release.
Process only needed sheets	`wb.RemoveWorksheet("SheetToIgnore");` before saving.
Avoid repeated saves	Convert once per workbook rather than per sheet.
Parallel processing (if you have many files)	Run conversions in separate threads/processes – each workbook conversion is thread‑safe.
Profile the workbook	Call `wb.CalculateFormula();` once, then measure the time spent on `Save`. This tells you if calculations dominate the runtime.
Cache frequently used fonts	Load custom fonts once via `FontConfig` and reuse the same `Workbook` instance.

Helpful Documentation Links

Convert Excel to PDF – https://docs.aspose.com/cells/net/convert-excel-to-pdf/
PdfSaveOptions reference – https://apireference.aspose.com/cells/net/aspose.cells/pdfsaveoptions
Optimizing memory usage – https://docs.aspose.com/cells/net/optimize-memory-usage/
Improving performance of large workbooks – https://docs.aspose.com/cells/net/performance-tips/

Next Steps

Profile your current conversion (stop‑watch around Workbook.Save).
Apply the options above gradually to identify the biggest gain.
If the workbook still takes too long, consider splitting it into smaller workbooks before converting.

Feel free to share a code snippet or a sample of the workbook (size, number of sheets, presence of charts/images) if you need more targeted advice. Happy converting!

John.He · September 8, 2025, 5:36am

@pavan-edu
Would you like to provide your sample files and runnable test code? Please compress files and code into zip format and upload them here. We will check it soon.

pavan-edu · September 8, 2025, 6:06am

here is the block of code used for rendering the excel document to pdf,

ExpertPdf.HtmlToPdf.PdfDocument.Document pdfAttachment = null;
using (MemoryStream sourceStream = new MemoryStream(attachment.FileData.ToArray()))
{
    Aspose.Cells.Workbook attachmentDocument = new Aspose.Cells.Workbook(sourceStream);
    attachmentDocument.Save(targetStream, Aspose.Cells.SaveFormat.Pdf);
    targetStream.Flush();
    targetStream.Seek(0, SeekOrigin.Begin);
}

if (targetStream.Length > 0)
{
    using (MemoryStream pdfStream = new MemoryStream(65536))
    {
        Aspose.Pdf.Facades.PdfFileStamp stamp = new Aspose.Pdf.Facades.PdfFileStamp(targetStream, pdfStream);
        RectangleF renderRegion = document.Pages[0].ClientRectangle;

        stamp.StartingNumber = document.Pages.Count + (!string.IsNullOrEmpty(sectionName) ? 2 : 1);
        stamp.AddPageNumber(new Aspose.Pdf.Facades.FormattedText("Page #", Color.Black, Color.Transparent,
            Aspose.Pdf.Facades.FontStyle.TimesRoman, Aspose.Pdf.Facades.EncodingType.Winansi, false, 9), 1,
            40, 40, 40, 40);
        stamp.AddPageNumber(new Aspose.Pdf.Facades.FormattedText(DateTime.Now.ToShortDateString(), Color.Black, Color.Transparent,
            Aspose.Pdf.Facades.FontStyle.TimesRoman, Aspose.Pdf.Facades.EncodingType.Winansi, false, 9), 5,
            40, 40, 40, 40);
        stamp.Close();

        pdfAttachment = new ExpertPdf.HtmlToPdf.PdfDocument.Document(pdfStream); //Creates a new pdf document with stream content.and appends to the orginal pdf document
    }
}

if (pdfAttachment != null)
{
    if (!string.IsNullOrEmpty(sectionName))
    {
        StringWriter writer = new StringWriter();
        HtmlTextWriter htmlWriter = new HtmlTextWriter(writer);
        htmlWriter.Write("<html xmlns='http://www.w3.org/1999/xhtml'>");
        htmlWriter.Write("<head>");
        htmlWriter.Write("</head>");
        htmlWriter.Write(string.Format("<body style='{0}'>", DocumentBodyStyle));
        RenderH2(htmlWriter, sectionName);
        htmlWriter.Write("</body></html>");
        htmlWriter.Flush();

        pdfConverter.PdfFooterOptions.PageNumberingStartIndex = document.Pages.Count;

        ExpertPdf.HtmlToPdf.PdfDocument.Document sectionDocument = pdfConverter.GetPdfDocumentObjectFromHtmlString(writer.ToString(), HttpContext.Current.Request.Url.AbsoluteUri); //if any section exists, //Creates a new pdf document with stream content.and appends to the orginal pdf document
		document.AppendDocument(sectionDocument); //Appends the sectionDocument to the orginal pdf document
	}

    document.AppendDocument(pdfAttachment); //Appends the sectionDocument to the orginal pdf document
}

1mb.zip (1.1 MB)

John.He · September 8, 2025, 6:45am

@pavan-edu
By testing with the following sample code and files on the latest version v25.8, we were able to save the file to PDF normally, taking approximately 11 seconds. Due to the large amount of content in the file, the generated result file contains 164 pages of content. 11 seconds is an acceptable output result. Please refer to the attachment. out_net.pdf (8.7 MB)

DateTime time = DateTime.Now;
MemoryStream targetStream = new MemoryStream();
Aspose.Cells.Workbook attachmentDocument = new Aspose.Cells.Workbook(filePath + "1mb.xlsx");
attachmentDocument.Save(targetStream, Aspose.Cells.SaveFormat.Pdf);
targetStream.Flush();
targetStream.Seek(0, SeekOrigin.Begin);

//attachmentDocument.Save(filePath + "out_net.pdf");

Console.WriteLine(DateTime.Now.Subtract(time).ToString());

The output:

00:00:11.3519227

Also, how long did your entire processing take? If the overall time consumption is too high, please check if other processing steps have taken up too much time.

pavan-edu · September 8, 2025, 7:22am

@John.He ,

Thank you for your response and appreciated.

In our requirement, we have form data with a N’number of fields in a form and including a file upload field and stores in the database on submit. While accessing the data from UI, we have given an option to the user to download the data along with the attached file content as appending it at the last. In this processing (excel to PDF) part is taking larger time.

I have share you the partial piece of code and with a sample content (1MB size). We are tried with multiple files with the sizes likely 10MB, 20MB, 35MB. For an instance, the 20MB file takes 8 to 9 mins of time to convert & download.
Of course, the processing time depends on the content file size, but which blocks the UI screen. So, Is there any way or alternate approach that can be increase the performance?

John.He · September 8, 2025, 7:43am

@pavan-edu
As the data increases, the conversion time from sample files to PDF will also increase accordingly. We have analyzed your example file and found that the data almost fills the area that needs to be exported. There is currently no better way. If you only need to export partial data of the file as a PDF, you can use the PdfSaveOptions.PageIndex and PdfSaveOptions.PageCount attributes. Please refer to the following example code and check the attachment. out_net.pdf (1.1 MB)

DateTime time = DateTime.Now;
MemoryStream targetStream = new MemoryStream();
Aspose.Cells.Workbook attachmentDocument = new Aspose.Cells.Workbook(filePath + "1mb.xlsx");
        
PdfSaveOptions saveOptions = new PdfSaveOptions();
saveOptions.PageIndex = 5;
saveOptions.PageCount = 10;
attachmentDocument.Save(targetStream, saveOptions);
targetStream.Flush();
targetStream.Seek(0, SeekOrigin.Begin);

//attachmentDocument.Save(filePath + "out_net.pdf", saveOptions);

Console.WriteLine(DateTime.Now.Subtract(time).ToString());

pavan-edu · September 8, 2025, 9:47am

@John.He ,

Are there any file size limitations when converting Excel content to PDF?
Does the file size affect the Excel-to-PDF conversion process?
Any reference, will helps us.

amjad.sahi · September 8, 2025, 10:19am

@pavan-edu,

There is no restriction on file size; you can seamlessly convert large Excel files to PDF using Aspose.Cells for .NET. However, please note that performance issue might arise when working with extremely large and complex workbooks containing heavy content, formulas and other binary data. You may also consider setting ‘PdfSaveOptions.OptimizationType’ to ‘PdfOptimizationType.MinimumSize’ while saving to PDF may help reduce the PDF size and enhance optimization.

pavan-edu · September 8, 2025, 4:13pm

Thank you for the details

amjad.sahi · September 8, 2025, 5:21pm

@pavan-edu,

You are welcome. If you have any additional questions or comments, please do not hesitate to contact us again.