How to make a PDF, photo or Office file smaller for upload or email

Guide · Updated 2026-11-10

Why files get big, what each compression method does to PDFs, images, Word, Excel and ZIP files, and how to hit an upload limit like 200 KB.

Open the File compressor Free, in your browser, nothing uploaded.

Email boxes cap attachments, and job, visa and exam portals often refuse anything over a few hundred kilobytes. The file compressor tool takes one file of almost any kind, works out what it is, and makes a smaller copy inside your browser, so private papers never leave your device. It is for anyone stuck at an upload box: students sending scans, staff mailing reports, families filing forms. To change a picture’s pixel size or crop it first, use the image resizer; to see whether a ZIP has room to shrink, try the ZIP checker; and to change a file’s type, reach for the file converter.

What it is

A file is big because of what is inside it. Text is tiny. Pictures are large, because every pixel (one coloured dot) needs storing. So most heavy files are heavy because of photos or scanned pages.

There are two ways to shrink data.

• Lossless compression finds repeats and writes them more briefly. Nothing changes when you open it. ZIP and the “Light” PDF setting work this way.
• Lossy compression throws away detail the eye barely notices, as JPG does. It saves far more, but the change cannot be undone.

For a scanned PDF, the tool redraws each page as a JPG picture at a set DPI (dots per inch). The pixel width of a page is:

pixels = page width in points ÷ 72 × DPI

where a point is 1/72 of an inch. Fewer dots per inch means fewer pixels, and a smaller file.

The saving shown at the end is (1 − after ÷ before) × 100, rounded to a whole percent. If nothing gets smaller, you get the original back.

How to use it

1. Press Choose a file, or drop one on the box. The tool shows its name, size and what it found, for example “Detected: PDF document”.
2. If there is more than one way to treat it, pick one under What should we do with it? For a PDF that is Compress the PDF or Pack into a ZIP; for Word, Excel or PowerPoint, Shrink the pictures inside or Pack into a ZIP.
3. Under How much to compress, choose Light, Recommended or Smallest. The line under each says what it does to your type of file.
4. For a PDF or an image with a size cap, turn on Fit an upload limit. Tap 100 KB, 200 KB, 500 KB, 1 MB or 2 MB, or type your own number of KB in the box.
5. Press Compress (or Pack into ZIP or Repack ZIP, depending on the file). A ring shows progress, and you can pop bubbles while you wait.
6. Read the Before, After and percent smaller, then press Download. Compress another file starts again.

A worked example

Arjun has a 6-page scanned A4 PDF of his school certificates. It is 4.8 MB, and the college portal accepts no more than 1 MB.

How big are the pages? An A4 page is 595.28 points wide and 841.89 points tall. With Recommended (150 DPI), each page becomes 595.28 ÷ 72 × 150 ≈ 1240 px by 841.89 ÷ 72 × 150 ≈ 1754 px, about 2.17 million pixels. With Smallest (100 DPI), it is about 827 × 1169 px, roughly 0.97 million pixels. That is (100 ÷ 150)² ≈ 44% of the pixels, so it is usually much lighter.

Fitting the limit. He turns on Fit an upload limit and taps 1 MB, which the tool reads as 1,024 KB, or 1,048,576 bytes. It first checks whether a lossless repack already fits. If not, it tries page pictures at 150, then 130, then 110 DPI, each a little lighter, and stops at the first that fits.

Reading the result. Suppose the result is 820 KB. The saving is (1 − 820 ÷ (4.8 × 1,024)) × 100 ≈ 83% smaller, and the file fits. If even 110 DPI were too big, the tool would say so and offer Go below anyway, which lowers quality further, his choice.

Where it is used

• Government, visa and job portals. Size caps of 100 KB to 2 MB are common for scans and photos.
• Email. Many mail services stop attachments at around 20 to 25 MB, and smaller files arrive faster.
• Reports and slide decks. Office files full of phone photos can shrink a lot when only the pictures inside are made lighter. The words, formulas and slides stay as they were.
• Data sharing. A large CSV or log file packed into a ZIP often drops to a fraction of its size.
• Phone storage. Photos re-saved at screen size free up space while still looking the same on a phone.

Common mistakes

• Choosing Recommended or Smallest for a form you still need to fill. These turn pages into pictures, so text cannot be selected and fill-in boxes and links are lost. Use Light for those.
• Deleting the original. Lossy changes cannot be undone. Keep the first copy in case you need it sharper later.
• Expecting a ZIP to shrink much. JPG photos and most ZIPs are already compressed, so repacking saves little.
• Mixing up KB and MB. 1 MB is 1,024 KB, not 100 KB. Read the portal’s limit carefully before you choose.
• Trying a locked file. Password-protected PDFs and documents cannot be opened. Save an unlocked copy in its own app first.

Questions people ask

Why did my PNG come back as a JPG? With Recommended or Smallest, a PNG with no see-through parts may be saved as JPG, which is much lighter for photos. Choose Light to keep PNG.

Do I need to unzip the packed file? Yes. Whoever receives a file made with Pack into a ZIP has to open the ZIP to use it. Most computers and phones do this with a tap.

What is the biggest file it takes? About 200 MB on a computer and 50 MB on a phone or tablet, because the whole file is held in memory while it works.