How to Reduce PDF Size for Email & Upload Portals

Why PDFs get so big

Not all PDFs are created equal. A PDF exported from Word with plain text might be 200 KB for ten pages. But most oversized PDFs share one cause: scanned pages. Every scanned page is a full photograph — often captured at 300 DPI or higher with minimal compression. A single scanned page can be 1–3 MB; a 20-page bundle of certificates easily tops 40 MB.

Other size culprits: embedded high-resolution photos, scanned pages saved in colour instead of greyscale, and pages scanned at resolutions far beyond what anyone will ever print.

The limits you need to beat

Size limits vary, but these are the ceilings most people hit:

• Email attachments: roughly 20–25 MB on most major providers (Gmail allows 25 MB). Many corporate inboxes are stricter — 10 MB is common.
• Upload portals: job applications, university admissions and government forms typically cap uploads between 2 MB and 10 MB per file. The exact number is always stated on the upload page — read it before you start.
• Messaging apps: document attachments on apps like WhatsApp allow far more (up to 2 GB), so messaging is rarely the problem — email and portals are.

Aim to land comfortably below the limit, not exactly at it — encoding overhead during sending can nudge a borderline file over the cap.

How to compress a PDF (3 steps)

1. Open the compressor. Go to our compress PDF tool in your browser. Your document never uploads — everything happens locally on your device, which matters when the file contains personal paperwork.
2. Choose a compression level. Start with a moderate setting. For scanned documents, moderate compression typically cuts the size by 60–80% while keeping text perfectly readable on screen and in print.
3. Download and verify. Save the compressed file, open it, and zoom into the smallest text. If everything is legible, check the file size — and only then attach or upload it.

Before you compress: remove what you do not need

Compression works on what is there — it cannot shrink pages that should not exist. Blank pages from scanning, duplicate pages, and cover sheets nobody asked for all inflate the file. Remove them first (a split PDF tool can extract just the pages you need), then compress what remains. Fewer pages means a smaller result at the same quality.

When compression is not enough: split the PDF

Sometimes the math simply does not work. A 60-page scanned thesis will not fit a 5 MB portal limit no matter how hard you compress — pushing compression that far would blur the text into uselessness. When that happens, split instead of squeezing:

• Split into logical parts. Divide the document into chapters or sections with our split PDF tool, and upload or send the parts separately. Name them clearly: "application-part-1.pdf", "application-part-2.pdf".
• Check if the portal accepts multiple files. Many do. If it accepts only one file, merge the compressed parts back together — the total will still be far smaller than the original.
• Consider whether the recipient needs everything. A landlord asking for "ID and proof of income" does not need your 40-page bank statement — the summary page may be enough, and it is a tenth of the size.

Tips for the smallest readable file

• Scan in greyscale, not colour, when the document is black text on white paper. Colour scans of text documents are several times larger for zero benefit.
• 150 DPI is plenty for documents that will be read on screen. Reserve 300 DPI for anything that must be printed sharply.
• Do not compress twice. Compressing an already-compressed scan degrades text quickly — always start from the original.
• If your scan came out as photos, convert them with JPG to PDF first, then compress the resulting PDF in one pass.
• Keep the original large file archived. If a recipient ever needs a print-quality version, you will be glad you kept it.