How to Compress a PDF to 300 KB (or 400 KB) Online Free

To compress a PDF to 300 KB, open compress PDF to 300 KB, choose your file, and download the result. The tool automatically finds the best quality that fits under 300 KB, in your browser, so the document is never uploaded. For a scanned certificate or a few pages of marksheets, 300 KB is a comfortable target and the text stays clear.

300 KB is one of the most common limits on Indian application portals, along with 100 KB, 200 KB and 500 KB. It is roomy enough that you rarely need tricks, but there are a few things that help when a long document will not fit.

How to reduce a PDF to 300 KB, step by step

Check what the portal really wants. Is it 300 KB per file or per page? Is a PDF required, or is JPG also allowed? Read the upload instructions once before you start.
Remove pages you do not need. Every extra page eats into the budget. Use delete PDF pages for blank backs of scans and duplicates.
Compress. Open compress PDF to 300 KB and choose your PDF. It starts working straight away.
Download and open it. Check that the size is under 300 KB and that small text such as dates and registration numbers is readable.

On a phone the steps are the same. Choose the PDF from the Files app (iPhone) or Downloads (Android) and the compressed copy is saved back to Downloads.

Under 300 KB: what fits

Think of 300 KB as a budget split across pages. These are rough guides; dense pages need more than sparse ones.

Pages	Budget per page	Typical result
1–2	150–300 KB	Sharp, even in colour.
3–5	60–100 KB	Clear text; colour photos inside the page soften a little.
6–10	30–50 KB	Readable, best with Black & white ticked.
10+	under 30 KB	Tight. Consider removing pages or splitting.

If your document is near the bottom of this table, tick Black & white. Greyscale pages are much smaller and text often looks cleaner.

Compress PDF to 300 KB per page

Some forms phrase it as "each page should not exceed 300 KB". Read this carefully, because it can mean two different things:

Each uploaded file under 300 KB. This is the most common meaning. If the form has separate upload slots for each document, compress each PDF to 300 KB.
Each page within a file under 300 KB. Rare, but it appears. A 4-page PDF could then be up to 1.2 MB. If the portal is strict about this, you can split the PDF into single pages with split PDF, compress each, and merge them back.

When in doubt, aim for the whole file under 300 KB. That satisfies both readings.

Compress PDF to 400 KB or any other size

The preset pages cover 100 KB, 200 KB, 300 KB, 500 KB, 1 MB and 2 MB, but the main compress PDF tool takes any number. Choose Target size in "Compress by" and type the limit, for example 400. The same works for 250 KB, 150 KB or 1.5 MB (enter 1536).

A good habit is to set the target slightly under the limit, say 390 KB for a 400 KB rule. Portals do not all count kilobytes the same way. Our tool treats 1 KB as 1024 bytes; a portal that counts 1000 bytes would see a 300 KB file from us as about 307 KB. Leaving a small margin avoids that surprise.

When you need to go lower: 200 KB

If the same portal has a stricter slot, for example 200 KB for a caste certificate and 300 KB for a degree, use compress PDF to 200 KB for that one. Our guide to compressing a PDF under 200 KB has tips specific to tighter limits.

Why some PDFs barely shrink

Our compressor works by rebuilding each page as a JPEG image. This is excellent for scans, which are images already, and often cuts their size by 70–95%.

It does less for PDFs that are mostly typed text, like a resume exported from Word. Those are usually small already. If the compressed version is not smaller, the tool tells you, and you should keep the original. For typed documents that are oversized because of an embedded photo, re-export from Word or Google Docs with a smaller image instead.

Two side effects to keep in mind:

Text stops being selectable in the compressed file, because each page is now a picture. Reviewers reading on screen will not notice.
Digital signatures do not survive. If the PDF was digitally signed (for example a DSC-signed certificate), compressing it this way invalidates the signature. Upload signed documents as they are.

Getting a better result from a scan

The compressor can only keep detail that is in the scan. A clean source gives a smaller, sharper file.

Scan with your phone's document scanner, not the regular camera, so the page is flattened and whitened.
Avoid shadows from your hand or phone.
Scan in greyscale if your scanner offers it.
Crop away the table or bed around the paper.

Common mistakes

Compressing a compressed file. Each round loses detail. Start from the original every time.
Picking the wrong file to upload. The compressed copy ends in -compressed.pdf. Rename it clearly.
Ignoring the format. If the portal says JPG, a PDF will be rejected. Convert with PDF to JPG first.
Uploading at the last minute. Portals often slow down close to the deadline, and a failed upload can cost you the slot.

Questions

How do I reduce a PDF to 300 KB on my phone?

Open the compress PDF to 300 KB page in your phone's browser, choose the PDF from Files or Downloads, and download the smaller copy. It works in Chrome and Safari without installing an app.

What does 'compress PDF to 300 KB per page' mean?

Some portals limit each page, or each uploaded file, to 300 KB. If the limit is per file and you have several pages, they all share that 300 KB. If it really is per page, split the PDF and compress each page separately.

How do I compress a PDF to 400 KB?

Open the compress PDF tool, choose Target size, and type 400 in the Max size box. You can enter any target, not only the preset values.

Can I compress a PDF to 300 KB without losing quality?

For a few scanned pages, yes in practice: 300 KB is a generous budget and text stays sharp. Some image detail is always lost, but usually not enough to see on screen.