How to reduce a PDF’s size for online forms

Why upload limits are so small

Application portals usually cap each file at a fixed size, often somewhere between a few hundred KB and 2 MB. Some also ask for a particular format or set separate limits for photos and signatures. Always read the limit on the form itself; it varies from portal to portal and sometimes from field to field.

A text PDF exported from Word is usually small enough already. The trouble starts with scans and phone photos. A scanned page is a picture of the page, and pictures are big.

What makes a scanned PDF large

Three things decide the size of a scanned page:

• Resolution. An A4 page scanned at 150 dpi is about 1240 × 1754 pixels. At 300 dpi it is 2480 × 3508 pixels: four times as many pixels to store.
• Colour. Full colour stores more information than greyscale, and greyscale more than black and white.
• Number of pages. Every scanned page adds roughly the same weight again, so a ten-page bank statement can be ten times the size of one page.

1. Scan with smaller settings

If you can scan again, this gives the cleanest result. On a scanner or a scanning app:

• Choose 150 to 200 dpi for ordinary documents. Text stays sharp on screen and the file stays small. Keep 300 dpi for documents with very small print.
• Choose greyscale or black and white unless colour matters, for example on a photo ID or a coloured stamp.
• Crop to the paper. A dark table around the page adds pixels and noise.
• Scan straight to PDF rather than photographing each page, where you can.

2. Compress the PDF you already have

When the PDF already exists, compressing is the quickest fix. A good compressor redraws each page at a lower resolution and saves it as a JPEG image, which shrinks scans a lot.

InTheTab’s compressor has three levels: Strong renders pages at 72 dpi, Balanced at 110 dpi and Light at 150 dpi. Start with Balanced, check the size it reports, and only go to Strong if you are still over the limit. If the result would be bigger than the original, it tells you and you keep the original.

Two things to know. Pages become images, so text in the result can’t be selected or searched, and links and fillable form fields are dropped. For a scan that makes no difference, but if you need to fill in the form fields of a PDF, fill them in and print to PDF first, or keep the original.

3. Split it into the parts the form asks for

Portals often have separate upload fields: one for an address proof, one for a mark sheet, one for an experience letter. If those are all in one long PDF, uploading each part separately also means each file is smaller.

Split PDF can extract the pages you choose into one new PDF, split by ranges into one PDF per range, or save every page as its own file. Pages are copied as they are, so splitting doesn’t lower the quality.

4. Shrink the images before making the PDF

If you are building the PDF from phone photos, make the photos smaller first. A modern phone photo has far more pixels than a document needs.

1. Open Resize image, set a maximum width (for example 1600 px) and a JPEG or WebP quality, and check the size before and after.
2. Put the smaller images into one document with JPG to PDF. Choose A4 with a small margin so the PDF prints at a normal paper size.
3. Still too big? Run the result through Compress PDF as well.

A quick checklist before you upload

• Open the final PDF and zoom in. Can you still read every number, date and signature?
• Check the size against the limit shown on the form, not a limit you remember from another portal.
• Don’t add a password unless the portal asks for one; it may not be able to open an encrypted PDF.
• Keep your full-quality original. You may need it again for a different portal.