How to Reduce PDF Size for Online Forms and Email (Step by Step)

Why PDFs get so large

A PDF that you typed or exported from a word processor is mostly text, which takes very little space. A PDF made from a scanner or phone camera is different: each page is a photograph. A high-resolution colour photograph of an A4 page can take hundreds of kilobytes or more, so a ten-page scan quickly reaches many megabytes. That is why size limits cause most trouble for scanned documents.

The method that works

1. Check the limit. Note the maximum size and any rules on format. Sizes in kilobytes or megabytes are common.
2. Remove what you do not need. Use Delete PDF Pages or Extract PDF Pages to keep only the required pages. Fewer pages mean a smaller file before any compression.
3. Compress. Open Compress PDF, add the file and start with Balanced. The tool turns each page into an optimised image, so it works well for scans and photos.
4. Check the result. Zoom in on signatures, stamps, numbers and small text. If it is still too large, try Small. If text looks blurry, use Good.
5. Upload the compressed copy and keep your original.

Which compression level should you use?

The three levels trade file size against clarity. Good keeps the most detail and is best for small print and tables. Balanced is the best starting point for certificates, ID scans and reports. Small gives the strongest reduction, but pages can look softer, so use it only when you must reach a strict limit and then check that everything important is legible. If you need a specific size, try one level, check the result size shown after compression, and adjust.

What you give up

Because this tool rebuilds pages as images, the compressed PDF may lose selectable and searchable text, working links and fillable fields. It still looks like your document and prints normally. For documents that must stay searchable or editable, keep the original for that purpose and use the compressed copy only for the upload that needs the small file. Password-protected PDFs cannot be processed, so use an unlocked copy that you are allowed to use.

Scan smarter to start with a smaller file

• Scan at a moderate resolution. Very high resolution creates large files with no visible benefit for reading.
• Use black and white or greyscale for text documents rather than full colour.
• Crop away dark borders and extra background before saving.
• If you start from photos, use Image to PDF with the Medium or Small File quality setting and keep the margin small.
• Compress each part separately and merge afterwards with Merge PDF if you need one combined document.

If it is still too large

Try these in order: remove more pages, choose the Small level, lower the render quality, split the document into two files if the form allows multiple uploads, or re-scan with a lower resolution. If your form needs images instead of a PDF, use the Exact KB Image Compressor to bring each image under the size limit.

Frequently asked questions