Compress a PDF in four steps
- Open the tool. Go to Compress PDF. Nothing to install, no account to create.
- Add your file. Drag it onto the page or click to browse. Files up to 25 MB are supported.
- Pick how hard to compress. Either choose a quality mode, or type the size you need — for example 2 MB — and let the tool search for the settings that land there.
- Check, then download. Open the result and zoom to 100% on a page with small text before you send it anywhere.
That last step is the one people skip, and it is the one that catches a scan compressed past the point of usefulness.
What compression actually does to your file
A PDF is a container. Inside it are text drawn as vector instructions, images stored as embedded bitmaps, fonts, and metadata. Compression almost never touches the text — vectors are tiny and already efficient. What shrinks is the image data: pictures get downsampled to a lower resolution and re-encoded at a lower JPEG quality, and duplicated resources get consolidated.
This explains the single most useful rule of thumb: if your PDF is big, something inside it is a picture. A scanned document is nothing but pictures, which is why it can lose 80% of its weight. A report typed in Word is nearly all vectors, which is why it will barely budge.
How much reduction to expect
- Scanned or photographed documents: 70–90% smaller.
- Presentations and brochures with photos: 40–60% smaller.
- Word or Google Docs exports: 10–20% smaller at best.
- Already-compressed PDFs: close to nothing, plus added artifacts.
When you need an exact size
Upload forms rarely say "make it smaller" — they say 5 MB, or 2 MB, or 500 KB. Guessing with quality presets means compressing, checking, and repeating. An exact-size mode does that loop for you: it compresses, measures, adjusts, and stops when the output is within a few percent of your target. Set the number the form demands, not a round number you assumed.
If a single document simply cannot reach the limit while staying readable, the better answer is usually to split it into two or three smaller uploads rather than crush it further.
Mistakes that ruin a compressed PDF
- Compressing the same file repeatedly. Each pass degrades images again without meaningfully reducing size.
- Overwriting your original. Compression cannot be reversed — the discarded pixels are gone. Always keep the source file.
- Compressing before you finish editing. Do your merging, page rotation, and signing first, then compress the finished document once at the end.
- Ignoring OCR. If a scan needs to stay searchable, compress gently — aggressive downsampling breaks text recognition.
Where your file goes
Compression can run entirely inside the browser tab, which means a confidential document never leaves your computer during the process. That is how PDF2Tool handles it: no upload, no server queue, no copy to delete later. If you use a different tool, check whether it uploads and how long it keeps files before you feed it anything sensitive.
Frequently Asked Questions
How do I compress a PDF to a specific size like 100 KB?
Use a tool with an exact-size mode and enter the target. Very small targets are only realistic for short documents; a 20-page scan will not reach 100 KB while staying legible.
Can I undo PDF compression?
No. Compression permanently discards image data. The only way back is your original file, which is why you should never overwrite it.
Will compression remove my password or signature?
A visible signature stamped into the page stays. Encryption usually has to be removed before processing, so protect the file again afterwards with the Protect PDF tool.
Why is my Word-exported PDF still large after compressing?
Because its weight comes from embedded fonts and vector text, not images. Compression has almost nothing to remove. Export with fewer embedded font subsets, or split the document instead.