Compress a PDF — or fit it under the exact size you need

Upload forms, exam portals and mail servers state their limit as a number, so Bindery lets you start from that number. Type it — “200 KB”, “1.5 MB” — or tap a chip, and Bindery looks for the highest-quality version of your file whose real size is at or under it. Lossless cleanup is tried first, so if that alone fits, no pixel changes. Every candidate is measured by actually writing the file on your device rather than estimated from a percentage, and the result shows the size reached and the setting used, such as images at 150 DPI, quality 60.

Prefer to choose for yourself? The three levels — Email & web, Balanced and lossless Print — are computed from your file as soon as you open Compress, each card showing its byte size. An image is only replaced when the new version is at least 8% smaller, and text is never turned into pixels. Bindery runs entirely in your browser — your file is never uploaded, so there is nothing to delete from a server afterwards.

How it works

1. Drop your PDF — the size of each of the three levels is computed from it on your device
2. Type your limit, such as 200 KB or 1.5 MB, or tap a chip — or simply pick a level
3. Download the result, or split the smallest version into parts if nothing fits

Fitting an exact size limit

Below the three level cards sits Or fit it under an exact size. Type any limit from 5 KB up — “200 KB”, “1.5 MB” and “1,5 MB” all work, and a bare number above 50 is read as kilobytes, 50 or below as megabytes — or tap a chip: 100 KB, 200 KB, 500 KB, 1 MB, 2 MB or 10 MB. Bindery then searches a ladder of ten image settings, from 220 DPI at high JPEG quality down to 50 DPI, plus the lossless pass:

1. Lossless first. If structure cleanup alone fits, that is the answer and no pixel changes.
2. Binary search. Otherwise it narrows in on the highest-quality setting whose real output is at or under the limit. Only the last three rungs are grayscale, so colour goes only when colour cannot fit.
3. A closer fit. If that setting leaves more than 20% headroom, one setting halfway to the next better rung is tried and kept when it still fits.

Each candidate is measured by writing the file on your device, and the sizes already computed for the level cards are reused, so a search usually takes three to seven attempts. The result card reads, for example, “Under 200 KB — Exact size”, with the real size and the setting: “images at 150 DPI, quality 60”, or “lossless — every pixel identical”. Bindery counts 1 KB as 1,000 bytes, so a file under its 200 KB is also under a portal that counts 1 KB as 1,024 bytes.

“Save these settings as my default” can store the limit itself — always under 2 MB, say. The size pages open Compress with the limit already set and start the fit on their own: 100 KB, 200 KB, 1 MB and 10 MB.

What actually makes a PDF big

Text and vector drawings are tiny. Almost all of a large PDF is images: photos placed at print resolution, scanned pages stored as full-page pictures, screenshots pasted into a report, the same logo embedded once per page. A smaller share is structure — uncompressed object tables, duplicated resources, objects left behind by earlier edits. Compression that works attacks both: it resamples images to the resolution the reader needs, re-encodes them at a sensible JPEG quality, stores identical streams once and rewrites the file with object streams.

That is why the honest answer to “how far can I reduce the PDF size?” depends on the file. An image-heavy deck has a lot to give; a text-only contract exported from Word is already close to its floor, and a tool that promises 90% on it is guessing. Bindery builds the candidates from your file and shows what each really weighs — and when a limit is out of reach, it tells you which part of the file is the reason.

The three levels, precisely

An image is only replaced when the re-encoded version is at least 8% smaller, so nothing is degraded for no gain and compressing twice never makes a file worse. Text is never rasterised. Scanned pages get mixed-raster compression on every lossy setting: the words become a sharp 1-bit text mask, the background is stored at low resolution, and any OCR text layer stays in place — so scans shrink further than plain JPEG recompression would allow and stay legible. Balanced and Email & web are also two rungs of the fit ladder, so an exact-size result follows the same rules. Measured results on sample files are published in the compression benchmark.

When nothing fits the limit

Compression cannot remove content, and some files cannot reach some limits whole. When even the lowest rung is over, Bindery shows the smallest size the file reaches and says why: either text, fonts and structure alone already take more than the limit, or the pictures still weigh a stated amount at the lowest setting. It then offers Split into parts under your limit, which opens Split with the smallest version loaded and the limit preset. Split measures each part by really writing it; a page that is over the limit on its own still becomes its own part, flagged so you know.

The other routes change what the file contains: extract only the pages the recipient asked for, or delete the ones that do not matter, then fit again. For attachments, compress for email covers the common mail limits. For portal rules beyond size, Unlock removes a password you know, Flatten bakes form fields into the page and OCR makes scanned pages searchable.

• The limit applies to the file you download. On the free plan the “Made with Bindery” line is added before the final size check, and if it tips the file over, the search runs again with less room.
• Check the result at 200% zoom before relying on it, especially signatures and small print on scans.
• Keep the original; the compressed file is a delivery copy.
• Compression leaves the metadata as it was — run Remove metadata if the author or title should not travel with the file.

Compressing in the browser versus uploading

Questions people ask

Can I compress a PDF to a specific size?

Yes. Type the limit under the level cards, or tap a chip such as 200 KB or 1 MB. Bindery tries lossless cleanup first, then keeps the highest-quality version whose real size, measured on your device, is at or under the limit. If none can fit, it tells you the smallest size the file reaches and why, and offers to split it into parts under the limit.

Will compression blur my text?

Not the text itself. Typed or exported text is never rasterised at any level or limit — only embedded images are resampled, so words stay sharp, selectable and searchable. On a scan, the words are part of the picture: they are kept as a 1-bit text mask so they stay legible, and any OCR text layer stays in place, but small print can soften at the lowest settings — check at 200% zoom.

Is my PDF uploaded to compress it?

No. The level sizes, the exact-size search and the compression itself all run in your browser tab, and the file never leaves your device. Bindery’s verify page shows how to confirm this yourself in the browser’s network panel while a job runs.

Does compressing a PDF reduce quality?

On the Print level, no: every pixel is kept and only the file structure is cleaned. Email & web and Balanced resample images towards 96 or 150 DPI, which is hard to see on screen for most documents but softens fine print on scans. An exact limit gets the highest quality that fits — lossless when that is enough. Typed or exported text is never affected on any setting.

Will fitting a limit turn my PDF black and white?

Only if colour cannot fit. The ladder keeps images in colour on its first seven rungs; the last three, at 72, 60 and 50 DPI, store them in grayscale, and the search only reaches those when every colour rung is over the limit. When it happens, the result card adds “grayscale” to the setting, so it is never a surprise.

Why did my PDF barely shrink?

Because it is mostly text, or its images were already compressed. Bindery shows the real result rather than pretending: a file that is already efficient stays close to its original size, and the Print card shows the honest lossless floor. If your limit is below what the text, fonts and structure need, Bindery says so, shows the smallest size the file can reach, and offers that smallest version or a split into parts under the limit.

Is compressing a PDF twice a bad idea?

With Bindery, no. An image is replaced only when the re-encoded version is at least 8% smaller, so a second pass either finds nothing to do or improves the file. Tools that recompress unconditionally are the ones that degrade files each time.

Can I see the quality before I download?

Yes. Once a level or an exact size is chosen, “Compare the quality with the original” shows both files side by side — the whole page, or both zoomed to 200% or 400% on the spot you click. Both are rendered on your device from the two actual files, so what you see is what you get.

Can I compress a whole folder to a size?

Yes. In Pipelines, add “Fit under a size”, set the limit and run it over your files: each one gets the best quality that fits, and a size report lists before and after for every file. Free pipelines take two files at a time; Pro removes the limit.

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