Compress PDF to 1000 KB
When an upload rule reads "maximum 1000 KB", it was usually written by someone thinking in kilobytes, and the number can mean three slightly different byte counts. This page starts at 1000 KB and shows when to type 975 instead.
Compress PDF
or drop PDF files here ·
Max 95 MB per file· Up to 20 files· Deleted after 30 minutes
Files are processed on our servers and deleted after 30 minutes.
Images above this DPI are downsampled. 150 is sharp on screen and fine for office printing; 72 is screen-only.
JPEG quality for re-compressed images. 70 keeps scanned text readable; below 40 artefacts appear around letters.
When aiming for a target size, image quality never drops below this; resolution is reduced instead.
How to use this tool
- 1
Upload the PDF
Add the file for the field that says 1000 KB. Up to 20 PDFs of up to 95 MB each can go in one batch.
- 2
Pick 1000 or 975
Target size is 1000 KB. If the rule says "less than 1000 KB" or a first attempt was rejected, type 975.
- 3
Compress and upload
Press Compress, download the PDF and upload it to the field; keep the original in case another field allows more.
"1000 KB" on a form is a developer's number, typed into a validation rule in kilobytes. Read it the way the server does and the PDF passes on the first try.
Why some forms say 1000 KB instead of 1 MB
Upload limits often surface exactly as they were configured. Many web frameworks take file limits in kilobytes: in Laravel, for example, the max validation rule for a file is measured in kilobytes, so a developer writes max:1000 and the error message tells applicants the file "may not be greater than 1000 kilobytes". Indian recruitment, admission and scholarship notifications often copy that number verbatim, which is why "PDF, maximum 1000 KB" is a familiar line on those forms.
The number looks like 1 MB, and most people treat it that way. That works most of the time, but not always: the server compares bytes, and 1000 KB can be multiplied out in more than one way. A file compressed to exactly 1 MB by a tool that counts in 1,024s is about 1,048,576 bytes, which is over any reading of 1000 KB.
1000 KB vs 1024 KB: the three readings of the limit
| The server reads 1000 KB as | Bytes allowed | Windows Explorer shows | Target that passes |
|---|---|---|---|
| 1000 × 1,000 bytes | 1,000,000 | 977 KB | 975 KB |
| 1000 × 1,024 bytes (Laravel-style) | 1,024,000 | 1,000 KB | 1000 KB |
| Loosely as 1 MiB | 1,048,576 | 1,024 KB | 1000 KB |
- Kibibyte (KiB)binary kilobyte · 1 KB in Windows
- Exactly 1,024 bytes. The IEC created the name so that "kilobyte" could mean 1,000 bytes, as "kilo" does everywhere else. Windows still labels kibibytes as KB, which is the root of most 1000 vs 1024 confusion.
Getting a PDF to 1000 KB with the right settings
With Target size at 1000 KB, the tool re-encodes the images in the PDF and stops when the file fits. For a document of up to ten scanned pages that usually means 150–200 DPI with JPEG quality high enough that no artefacts show at normal zoom. Text, vector drawings and links are not touched, and Subset fonts and Remove metadata trim the rest.
Longer scans need Convert to grayscale to keep resolution up. If the reviewer only needs a black-and-white copy, convert the PDF to black and white before compressing. When a different field on the same form allows 1 MB or more, use compress PDF to 1 MB for that one instead of reusing this target.
1000 KB PDF questions
Is a 1000 KB PDF limit stricter than a 1 MB limit?
Usually by a little. 1000 KB is at most 1,024,000 bytes, while 1 MB can mean as much as 1,048,576. The gap is about 24 KB, invisible in quality but enough to fail an upload, so treat 1000 KB as its own target rather than rounding it up to 1 MB.
Why does Windows show my 1,000,000-byte PDF as 977 KB?
File Explorer divides by 1,024 and rounds up, so 1,000,000 bytes appear as 977 KB. The same file appears as 1 MB in macOS Finder, which counts in thousands. The portal sees only the bytes.
What does a 975 KB target protect against?
A site that reads 1000 KB as 1,000,000 bytes. A file of 975 KB is under one million bytes whichever way the kilobyte is counted, so it passes every reading of the limit.
My form allows 1000 KB, but the PDF has 30 scanned pages. Will it fit?
Often only in grayscale at a reduced resolution, around 100–120 DPI, where small print starts to blur. If the form has more than one upload field, split the file; how to split PDF files shows how to cut it by page range.
Can I compress several PDFs to 1000 KB each at the same time?
Yes. Upload up to 20; each one gets its own 1000 KB target, and you can download them separately or together as a ZIP. Files are deleted automatically 30 minutes after processing.