Pick the size the form in front of you actually names. If a portal says PDF, max 100 KB, use the 100 KB preset; if it says 200 KB, use the 200 KB preset; and so on. That sounds obvious, and it is the whole decision: each of the four preset tools chases one specific byte cap with the same honest engine, and choosing a smaller cap than the form demands only costs you quality for no benefit.
The four tools are Compress PDF to 100 KB, Compress PDF to 200 KB, Compress PDF to 500 KB and Compress PDF to 1 MB. All four run entirely in your browser, start with a lossless rebuild, and then work down a measured ladder of lower resolutions and JPEG quality, stopping at the first result that fits — so you always get the best quality that meets the cap, and a plain status line if the cap genuinely cannot be met.
Start from the cap on your form: 100 KB · 200 KB · 500 KB · 1 MB. Free, no sign-up, no upload — each tool reports its final size and whether the cap was met or honestly missed.
How the four presets work: one engine, four caps
Every preset follows the same sequence, which is why the choice between them is only about the number. First, the tool tries the free win: rebuilding the PDF structure losslessly, with no visual change and text untouched, and weighing the result. If that already fits under the cap, you are done, and the text stays selectable. Only if the lossless rebuild misses the cap does the tool re-render pages as JPEG images at descending resolutions and qualities — starting around 150 DPI at high JPEG quality and descending through eight steps to roughly 45 DPI at low quality on the 100 KB tool — weighing the real output after every step and stopping at the first fit.
That measurement-first design is the honest part. Reaching a byte cap is a measurement process, not a promise: input density decides what is possible, and a many-page dense document simply sums past a small cap at any readable quality. When the ladder ends without a fit, the tool hands you the smallest version it could make and says so in the status line, rather than shipping an unreadable file at the cap or pretending it succeeded. Your original is never modified, regardless of the result.
The four caps side by side
The caps are not four flavours of the same job; they map to four different kinds of form. The 100 KB tool exists for the strictest portals, the kind that reject anything over 100,000 bytes. The 200 KB tool is, by its own tool page's account, the cap most government and bank portals actually set. The 500 KB tool is the cap most application and visa portals impose, and the classic compromise between legibility and storage. The 1 MB tool is the email-friendly cap: comfortably below every common attachment limit of 10 to 25 MB, and quick to send and receive.
Quality follows the cap in the same order. At 500 KB and 1 MB, most real documents fit in the first few ladder steps, so results usually look close to the original — the 500 KB tool page notes that fitting early steps keep roughly 120 to 150 DPI, which reads well on screen and prints acceptably for forms. At 200 KB, files fit at middle ladder steps, still crisp for documents. At 100 KB, the ladder may have to descend a long way, and small text, while still legible in the tool's example, is the price of fitting a strict cap at all. Picking a cap smaller than the form demands buys you nothing and spends quality you did not need to spend.
| Cap | Best for | What to expect |
|---|---|---|
| 100 KB (100,000 bytes) | Strictest portals that name 100 KB | Hardest fit; ladder may descend to about 45 DPI; small text still legible in the tool's example, but check readability before submitting |
| 200 KB (200,000 bytes) | Most government and bank portals | Twice the room of 100 KB, so more files fit at higher ladder steps with better quality |
| 500 KB (500,000 bytes) | Application and visa portals | Most documents fit in the first few steps at roughly 120–150 DPI; close to the original |
| 1 MB (1,048,576 bytes) | Email and general uploads | Most files fit early at near-original quality; the just-make-it-emailable choice |
Tool-page worked examples: final size under each cap (KB) — hover or tap each bar for details.
Worked examples from the tools themselves
Each tool page carries its own worked example, and together they show the ladder behaving exactly as described. A two-page application form exported at 480 KB must fit a portal's 100 KB cap; the ladder lands it at 96 KB, with small text still legible, and the portal accepts it first try. A scanned three-page ID document at 1.1 MB needs to fit a bank portal's 200 KB limit; it lands at 187 KB on a middle ladder step, documents crisp, portal satisfied. A 3.4 MB property deed scan must go through a 500 KB land-registry upload; it fits at 462 KB on an early ladder step, with seals and signatures still sharp enough to read comfortably. A 6 MB photo-heavy portfolio needs emailing; at 940 KB it makes the inbox limit with photographs that still look like themselves, because the ladder stopped as soon as the cap was met, not before.
Read those four examples as a pattern, not as promises for your file. The same tool on a denser file may stop higher on the ladder or miss the cap honestly — that is the engine working as designed, and the status line will tell you which happened. If your file is already under the cap you picked, the tool says so and simply rebuilds it losslessly, which is the best possible outcome and costs you nothing in quality.
Before you compress for a portal, check whether the portal's cap is per file or per upload, and whether it counts kilobytes as 1,000 or 1,024 bytes. The presets use 100,000, 200,000 and 500,000 bytes, and 1,048,576 bytes for 1 MB — matching the form's number matters more than the label on the button.
The quality cost you must know before you compress
Reaching a hard size cap usually means re-rendering pages as images, and text in a strongly compressed result is not selectable. That is the single most important trade-off in this whole family of tools, and every tool page states it plainly. If you need selectable text — for a document you will search, copy from or archive as text — try the general Compress PDF tool's Optimize mode first, which squeezes gently and keeps text alive, before reaching for a hard cap preset. Only use a preset when a form names a number you must hit.
The same trade-off runs the other way for scans. A scanned document is already images, so the ladder costs it less in practice: there was no selectable text to lose. A born-digital text document squeezed to 100 KB, on the other hand, gives up its text layer for the sake of the cap, so keep an uncompressed original alongside any ladder result you submit. The status line never hides which path produced your file — lossless or ladder — so check it before you upload, not after.
Never compress your only copy to a hard cap. Keep the original, compress a copy, and check the result's readability at 100% zoom before submitting — especially at 100 KB, where the ladder's lowest steps are a last resort, not a default.
When the cap cannot be met: what to do next
If the status line says the smallest reachable size is still over the cap, you have three honest options, and the tool pages name the main one: split the document. Split PDF by Size divides a file into parts under a size cap you set, measured from real output bytes, so each part can pass the portal separately. That works when the form accepts multiple uploads; when it accepts only one file, splitting does not help, and the remaining options are to reduce the document itself — fewer pages, lower-resolution source images, or a shorter version — or to ask the recipient whether a larger cap or a different channel is available.
What you should not do is run the result through a second compressor hoping for a miracle, or accept an unreadable file just because it fits. A form that cannot read your document will reject it just as surely as a form that cannot accept its size, and an unreadable submission wastes more time than an honest conversation with the recipient about the cap. If the general compressor's gentle Optimize mode already gets you under the cap, prefer it: a file that fits without the ladder keeps its text and its quality, and that is a better submission than a smaller file that lost both.
For the full gentle-versus-hard comparison, see How to Compress a PDF Online, and before any submission with a hard deadline, run Validate PDF on the final file: a structural health check catches the problems a size check cannot, like a file that fits the cap but fails a portal's parser.
Match the cap on your form, not a guess: 100 KB · 200 KB · 500 KB · 1 MB — all free and browser-only. And if your own website needs document handling this honest for your customers, talk to Asad Webs about your project.
Frequently Asked Questions
Why are there four preset tools instead of one box?
Because the cap in front of you is a specific number from a form — one click with that number beats configuring a general compressor under time pressure. The engine is identical; only the cap differs.
Will my text stay selectable after compression?
Only when the lossless rebuild fits the cap. Ladder results are rendered images of the pages — text is visible but not selectable. The status line states which path your result took.
What happens if my PDF cannot fit the cap?
You get the smallest result the ladder could reach, plus a plain explanation in the status line. Splitting the document is the usual next step, or reducing the document itself.
Is 1 MB a safe email size?
Yes — comfortably below every common attachment limit of 10 to 25 MB and quick to send and receive; it is the just-make-it-emailable cap.
Why do portals pick 500 KB?
It is the classic compromise between legibility and storage — most of the hard-cap forms on the web use 100, 200, 500 KB or 1 MB, and this preset family covers each with its own tool.
Is my PDF uploaded when I compress it?
No — compression runs entirely in your browser on your device, for all four presets and for the general Compress PDF tool.
Sources: Asad Webs Compress PDF to 100 KB, 200 KB, 500 KB and 1 MB tool pages (caps in bytes, ladder description, worked examples, selectable-text warning, split suggestion — verified live 2026-11-03); Asad Webs Compress PDF, Split PDF by Size and Validate PDF guides linked in the text.
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