How to compress a PDF to 200 KB, 100 KB or 50 KB

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To get a PDF under a limit such as 200 KB, 100 KB or 50 KB, open Docshar Compress, add the file, type a target a little below the limit (for example 95 KB for a 100 KB limit), and click Compress PDF. Docshar tries gentler settings first and stops at the best quality that fits. If the file still will not fit, you can allow pages to be turned into images, remove pages you do not need, or re-scan the document at a lower resolution.

How small a PDF can go depends on what is inside it, so no tool can promise an exact size for every file. A one-page scan usually reaches 100 KB easily; a ten-page scan at 50 KB may only be possible at a quality that is hard to read. This guide explains what to try, in what order, and how to check the result before you upload it.

Docshar compresses the file in your browser; it is not uploaded to Docshar's servers (see the privacy policy). Without an account, files can be up to 10 MB and 30 pages.

Compress a PDF to a target size

1. Open the Compress tool. Go to Docshar Compress on your phone or computer.
2. Add your PDF. Click Choose file or drag the PDF onto the page. Under the size box Docshar shows the current size, for example "Current size: 1.80 MB. Enter a smaller size."
3. Enter the target size. In Target file size, type a number and choose KB or MB. Docshar fills in half the current size as a starting point; replace it with your own target, a little below the form's limit.
4. Decide whether pages may become images. Allow turning pages into images to reach the size is off by default. Leave it off for a first try. Turn it on for very small targets such as 50 KB, or when the first try did not fit, if you do not need the text to stay selectable.
5. Compress and check the result. Click Compress PDF. The result says, for example, "Compressed from 1.80 MB to 92.4 KB (target 95.0 KB)." Click Download, open the file and zoom in to check it is readable.

Why upload forms set size limits

Exam registrations, scholarship and recruitment portals, KYC forms and government services often accept only small files, typically stated as a maximum such as 50 KB, 100 KB, 200 KB, 500 KB or 1 MB. Limits like these keep uploads quick on slow connections and keep storage manageable for services that receive a very large number of documents. Each portal sets its own rules, often different for photos, signatures and supporting documents, and they can change between application cycles. Always read the current instructions of the portal you are using; compressing a file only makes it smaller, it does not make it acceptable to a particular portal.

Check the current size of your PDF

Before compressing, find out how far you have to go. A 300 KB file to 200 KB is easy; a 6 MB phone scan to 50 KB is a big step.

• Windows: right-click the file in File Explorer and choose Properties. "Size" shows the size and, in brackets, the exact number of bytes.
• Mac: select the file in Finder and choose File > Get Info (Command-I).
• iPhone and iPad: in the Files app, touch and hold the file and choose Get Info.
• Android: in your file manager app, open the file's menu (often the three dots) and look for Details, Info or Properties. The wording differs between phone makers.
• In Docshar: every tool lists the file with its size and page count after you add it, and Compress shows "Current size" under the target box.

KB, KiB and why to aim below the limit

"KB" is used in two ways. Sometimes 1 KB means 1,000 bytes; sometimes it means 1,024 bytes (strictly called a kibibyte, KiB). Windows File Explorer and Docshar count 1 KB as 1,024 bytes, while macOS Finder counts 1 KB as 1,000 bytes, so the same file can show slightly different numbers on different devices.

The difference matters right at the limit. A Docshar target of 100 KB means up to 102,400 bytes. If a portal counts 100 KB as 100,000 bytes, a file of 101,000 bytes would pass in Docshar's terms but be rejected by the portal. The simple fix is to aim a few per cent lower:

The smallest target Docshar accepts is 5 KB, and the target must be smaller than the current file.

What Docshar does to reach the size

Compress works in stages and stops as soon as the file fits:

1. Lossless clean-up. It removes data nothing uses any more (for example leftovers from earlier edits and page thumbnails) and packs parts that were stored uncompressed. Nothing visible changes.
2. Re-compressing photos and scans. It saves the images inside the PDF at step-by-step lower quality and resolution, starting gently. Text and vector drawings are not touched, so typed text stays sharp.
3. Pages as images (only if you allow it). If shrinking the images is not enough and Allow turning pages into images to reach the size is ticked, Docshar estimates the result first and then renders the pages as images at decreasing resolution. Text on those pages can no longer be selected or searched. Docshar skips this stage for PDFs that are mostly plain text, because pages as images would come out bigger.

If the target cannot be reached, Docshar still offers the smallest version it made and tells you why, for example that a large part of the file is embedded fonts, or images in a scanner format (such as JPEG 2000, JBIG2 or CMYK) that the browser cannot re-compress directly.

How scans and photos affect the size

Almost all of the size of a scanned document is the image of each page. Three things decide how big that image is:

• Resolution. A page scanned at 600 DPI has four times as many pixels as the same page at 300 DPI. For a typed certificate or mark sheet, 150 to 200 DPI is usually readable on screen; small print may need more.
• Colour. A colour scan stores three colour channels; a grayscale scan stores one. Black-and-white (1-bit) scans of plain text are smaller still.
• Clutter. Shadows, table texture, paper grain and noise all cost bytes. A photo cropped to the edges of the paper, in even light, compresses far better than one showing the desk around it.

Docshar Compress has no grayscale switch, so if you need grayscale, choose it when you scan: most scanner apps and printers offer a "Grayscale" or "Black and white" setting.

If the file stays above the target

Work through these in order. Each one keeps the document more readable than simply forcing a lower target.

1. Allow pages as images. Run Compress again with Allow turning pages into images to reach the size ticked. For a scanned ID or certificate, losing selectable text rarely matters.
2. Remove pages you do not need. Blank backs, instruction pages and duplicates all add size. Remove them with Delete Pages, or keep only the required pages with Extract Pages, then compress again.
3. Re-scan at a lower resolution, or in grayscale. Starting from a smaller, cleaner scan gives better quality at the same size than squeezing a huge colour scan.
4. Split the document, if the portal lets you upload several files. Split by size makes parts under a maximum size (set in MB), and Split cuts by page ranges. See how to split a PDF.
5. Ask or check the instructions. Some portals accept a larger file for multi-page documents, or a different format. Do not assume; check.

Readability versus size

Every portal ultimately needs someone to read your document. A file that fits the limit but has blurry marks, an unreadable seal or a smudged signature can cause more trouble than a file that was too big. Use the largest size the portal allows rather than the smallest you can reach: if the limit is 200 KB, a 190 KB target looks better than 60 KB.

Check the compressed PDF before you submit it

• Open the downloaded file (its name ends in _compressed.pdf) in a normal PDF viewer, not just the preview thumbnail.
• Zoom to 100% or more and read the smallest text: names, dates, roll or registration numbers, marks and stamps.
• Check photos, signatures, seals and any QR code are clear.
• Confirm the size in your file manager, and that it is below the limit in the portal's own terms (see KB vs KiB above).
• Check the page count is what the form expects.
• Keep the original, uncompressed file. If a portal or office later asks for a clearer copy, you will need it.

Limitations

• Exact sizes cannot be guaranteed. The result depends on how many pages there are, how the file was made, the images in it and the fonts it embeds.
• PDFs that are mostly text are already stored efficiently and often cannot shrink much. Large embedded fonts can only be removed by turning pages into images.
• Some scanner image formats cannot be re-compressed in the browser; Docshar says so when this happens.
• Pages turned into images lose selectable and searchable text. You can make them searchable again with OCR, which adds size.
• Compressing changes the file. If a document carries a digital signature (some downloaded certificates and e-documents do), changing it in any tool can make that signature show as invalid. If a portal wants the original signed file, upload it as you received it.
• File and page limits depend on your plan: 10 MB and 30 pages without an account, 10 MB and 50 pages with a free account. Bigger limits are available on paid passes, see Pricing.

Tips

• Starting from photos? Convert them with JPG to PDF first, then compress the PDF. For ID cards, see converting Aadhaar, PAN or a photo to a PDF under 1 MB.
• If you have to submit several documents as one file, merge them first and compress the merged file once, rather than compressing each one to the limit.
• A protected PDF has to be unlocked before it can be compressed. See how to remove a password from a PDF you own.

Frequently asked questions