Compress PDF to under 100 KB

How many pages fit in 100 KB

Think of 100 KB as a budget that all the pages of your PDF share. A one-page certificate gets the whole 100 KB. A four-page marksheet set gets about 25 KB a page, and a scan of 14 pages only about 7 KB a page. The fewer pages, the clearer each one stays.

We measured this on three real scans, all A4 pages scanned at 300 dpi: a colour contract with a picture and a blue signature, a colour report full of small text, and a grayscale report. We made copies with 1, 2 and 4 or 6 pages and put each one under 100 KB. Each cell shows the word the result gave and the pixels per inch (ppi) the scanned pages kept:

Every one of these fitted under 100 KB, between 84 KB and 98 KB. Two things stand out:

• Each time the pages double, sharpness drops by about a quarter. The contract went from 127 to 98 to 73 ppi as it went from one page to two to four.
• Busy pages need more room than plain ones. The reports are packed with small text, so one report page kept 98 ppi where one contract page, with more white paper, kept 127.

Past six pages, 100 KB gets tight. We joined all three scans into one 14-page PDF of 23.1 MB. It still went under 100 KB (94 KB, in 12.1 seconds), but only at 38 ppi, and the result said Rough. How a page looks shows what that means in practice.

Papers people shrink to 100 KB

Exam, job, admission, scholarship and government forms often ask for each document as a separate PDF with a small limit. Rules differ from form to form and change from year to year, so always read the form's own notice. These are the papers that most often have to go under 100 KB, with what to do for each:

• Aadhaar card. Put the front and the back on one page if the form wants one file: scan both sides together on a scanner, or use the printed letter. One page gets the whole 100 KB.
• PAN card, voter ID, driving licence. One small card on one page. Crop the scan close to the card if you can, so the card fills the page instead of white paper.
• Marksheets and pass certificates. Usually one page each. If the form has one upload for Class 10 and another for Class 12, make two PDFs: each gets its own 100 KB.
• Caste, income, domicile and EWS certificates. One or two pages. A certificate downloaded from a state portal is often a typed PDF already well under 100 KB: check its size before you change anything.
• Experience and relieving letters, offer letters. One or two pages. Leave out blank second pages and envelope scans.
• Bank passbook front page or a cancelled cheque. One page. Scan only the page with your name, account number and IFSC code.
• Photo ID with a photograph on it. Fits, but the face is the first thing to go soft. See Photos and signatures.

Notice the pattern: almost everything a form wants at 100 KB is one or two pages. That is the size the table above shows staying Good or Readable. If your file has more pages than the form needs, removing them is the single biggest help.

How a page looks at 100 KB

We opened each result and looked at it at normal zoom, next to the original scan. Here is what we saw on our sample contract, page 1, which has a heading, numbered paragraphs, a colour picture, a blue signature and a small "Page 1 of 4" line at the bottom:

So Readable really means readable on a screen, and Rough means stop and check. Size of print matters too: big headings survive longest, while small print and light ink go first.

Typed text is different. If your PDF was made on a computer, its words are real text, not a picture, and stay perfectly sharp at any size. Only the pictures in it, such as a logo or a photo, get softer.

Check it before you upload

The result line under your file tells you most of what you need. Read it in this order:

1. "Under 100 KB" in green. It fits. "Over 100 KB" means it could not get that small: see When it says Over.
2. The two sizes, before and after, like 9.96 MB to 91 KB.
3. The word after "Pictures". Sharp or Good: upload it. Readable: fine for most forms, but check small numbers. Rough: check every number, or follow When it says Rough.

Then open the new file, the one whose name ends in -100KB.pdf, and look at it the way the person checking your form will:

• Zoom in until the page is about as big as the real paper. On a phone, spread two fingers until one line of text fills the screen width.
• Read every number the form depends on: roll number, registration number, date of birth, marks, certificate number, account number.
• Find the stamp and the signature. They should still be visible as a stamp and a signature, even if softer.
• Count the pages and check their order. The new file has exactly the pages of the old one.

If something isn't clear and the form allows a bigger file, pick the bigger size at the top of this page. Files you already added are done again straight away, so there is nothing to choose twice.

When it says Over 100 KB

"Over" means the file can't get under 100 KB, and you are looking at the smallest version possible. It nearly always happens with typed PDFs, not scans. Scans are pictures, and pictures can always be made smaller. Typed PDFs are mostly text and fonts, which we copy as they are so that words stay sharp, and fonts take room that no setting can win back.

What to do, from the easiest:

1. Upload only the pages they ask for. Take the pages you need out of the PDF with Split PDF and try again. Fewer pages means less text and fewer fonts.
2. Make the page a picture, then shrink it. This works well for one or two pages. We turned that 302 KB textbook page into a JPG with PDF to JPG at Normal, put the JPG back into a PDF with JPG to PDF (213 KB), and then it went under 100 KB here: 85 KB, Good, and the maths still looked clean. The words are no longer text you can search or copy, which an upload form doesn't need.
3. Don't do that with long documents. The same trick on all 14 pages of the research paper gave 89 KB, but Rough at 32 ppi: only the title could be read. A long document needs a bigger limit or fewer pages.

If a form insists on 100 KB for a long typed document, ask whether a summary page or the first page is enough. Many forms only need proof, not the whole document.

When it says Rough

Rough means the file fits, but its scanned pages had to drop below 45 ppi. Small print may be unreadable. Here is what helps, with what we measured:

• Fewer pages helps most. Our 14-page set was Rough at 38 ppi. The four contract pages on their own kept 73 ppi, and one page kept 127.
• Separate uploads, if the form has them. Each file gets its own 100 KB. Split PDF can save each page as its own PDF; then add them all here at once, and each one gets its own 100 KB copy.
• A grayscale scan helps only a little. We made a grayscale copy of our four-page contract. Under 100 KB it kept 76 ppi instead of 73: a small gain. Scan in grayscale if it is easy, but don't expect it to rescue a Rough file.
• Start from the original scan. A copy that was already squeezed for another form has lost detail for good. Keep your first scan and always start from it.
• Crop away empty paper and backgrounds. A card photographed on a table carries the table too. Scanner apps on phones can crop to the paper's edge before saving.

A Rough file is still better than a refused one, so if the form gives you no other choice, upload it after checking the numbers you can still read.

Photos and signatures

Your passport-size photo and signature are usually separate uploads. Most forms ask for them as JPG pictures with their own size and pixel rules, not as a PDF. This page works on PDFs only, and NoUploadPDF has no tool yet that resizes a JPG to a number of KB. Use the form's own instructions, or a photo editor on your phone, for those two.

A photo or a signature inside a PDF is part of the scanned page, so it gets as soft as the rest of the page. In our tests:

• The colour picture on page 1 of our sample looked like the original when that page went under 100 KB on its own (127 ppi). In the four-page copy (73 ppi) it lost its fine edges but kept its colours. In the 14-page copy (38 ppi) it broke into visible square blocks.
• The blue signature stayed a clear blue line on one page and a lighter but clear line on four pages. On 14 pages it turned grey and blotchy. Thin, light ink suffers first, so sign with a dark pen.

If a form wants a photo as a PDF, for example a document photographed with your phone, put the photo into a PDF with JPG to PDF, then add that PDF here. A single photographed page is one page, so it usually keeps Good or Readable sharpness. Crop the photo to the paper first, so that 100 KB is spent on the document, not the table it lay on.

Several documents, each under 100 KB

Many forms have one upload slot per document, each with the same 100 KB limit. You can do all of them in one go:

1. Choose all your PDFs at once, or drop them onto the page together. Each one becomes its own row.
2. They are done one after another, each to its own copy under 100 KB, with its own Download button and its own result word.
3. Download each one. The names keep the original name and add -100KB, like marksheet-class10-100KB.pdf, so you can tell them apart in the upload window.

If everything was scanned into one PDF, take it apart first with Split PDF, which can save every page, or every few pages, as its own PDF. Then add the parts here.

If the form wants everything in one file, the opposite applies: join the papers with Merge PDF first, in the order the form lists them, and then bring the joined file under 100 KB. The limit is checked on the file you upload, so always shrink last. Remember the budget: four papers in one 100 KB file get about a quarter each.

100 KB or a bigger limit?

Some forms say "up to 200 KB" or "between 50 KB and 300 KB". Then aim for the biggest size they accept, not 100 KB. Twice the room makes a visible difference, as these pairs from our tests show:

For 200 KB there is a page set up for it: Compress PDF to 200 KB. Or pick 200 KB, 500 KB or Other right here. For any other limit, or to change the paper size to A4, use Resize PDF, and when there is no limit at all, for example for email, our PDF compressor lets you choose a quality level instead.

There is also a 50 KB choice for very strict forms. It works the same way, with half the budget, so expect one or two pages at most to stay Readable.

How 100 KB is counted

There are two ways to count a kilobyte: 1,000 bytes or 1,024 bytes. Websites use either. We use the stricter one: "under 100 KB" here means at most 100,000 bytes, which is under 100 KB on every website, whichever way it counts. So there is no need to pick 95 KB "to be safe".

Your phone or computer may show a slightly different number for the same file. The sizes on this page, like "98 KB" after a file, are counted in 1,024-byte kilobytes, like most file apps count. A file of 99,933 bytes, from one of our tests, shows as 98 KB here, as 97.6 KB in some apps and as 99.9 KB in others. All three describe the same file, and all of them are under the limit.

The resizer also lands close to the limit on purpose: within 15% under it, so usually between 85 KB and 100 KB. A much smaller file would be blurrier than needed, because it would throw away detail the limit had room for.

Your papers stay private

A 100 KB upload is usually your most private paper: an Aadhaar card, a PAN card, a caste certificate, a bank page. Most sites that shrink PDFs upload the file to their computers first. This one doesn't. The work is done by a program running inside your browser, on your phone or computer, and the new file is saved straight to your device.

You can test it: once this page has loaded, switch off mobile data and Wi-Fi, then make your file. It still works, because nothing needs to be sent. There is no account, no sign-up and no watermark on your document. Our privacy policy has the details.

Limits

• Typed PDFs have a smallest size set by their text and fonts. Our 14-page research paper could not go below 766 KB.
• Many scanned pages share one budget: 14 pages fitted, but Rough.
• PDFs that need a password to open can't be compressed yet. Remove the password in your PDF reader first.
• A digital signature in the PDF stops being valid when the file changes. A signature scanned as part of the page is just a picture and stays.
• This page makes PDFs smaller. It doesn't resize JPG photos, and it can't make a file bigger if a form sets a minimum size.
• Big scans take longer, because each try is a full pass over the file: our 23.1 MB set took 12.1 seconds.