Dummy File Generator
This dummy file generator creates a test file in seconds: choose a size and a file type and the file is built on your device with exactly the number of bytes you asked for. Use it to test upload limits, email attachments, transfer times or storage space without touching real documents.
Source: ISO 32000-1 / Adobe PDF Reference – Dateistruktur (Header, Objekte, Querverweistabelle xref, Trailer). Updated: .
How it is calculated
A test file or dummy file is a file with arbitrary content and an exactly specified size. It is needed when you want to see how a system copes with a file of a certain size: does it still fit as an email attachment, does the upload form accept it, how long does the transfer take?
Which file types are available
- PDF, PNG, ZIP: these files are formally valid and open normally. The requested size comes from filler bytes that programs ignore or that sit invisibly in the file. That matters when a form accepts only certain extensions or file headers.
- Text file: lines with running numbers, easy to read and open in any editor.
- Zero bytes: a binary file made only of zeros. It compresses very well.
- Random data: random bytes cannot be compressed and suit realistic transfer and storage tests.
1024 or 1000 bytes per kilobyte?
By default the tool counts in binary: 1 KB is 1024 bytes and 1 MB is 1024 × 1024 bytes. That is how Windows and most upload limits count. To mimic storage vendors’ figures, switch to decimal (1 KB = 1000 bytes). How long a file of that size takes over a network is shown by the download time calculator; for packing and unpacking there is the ZIP tool.
Frequently asked questions
How do I create a file of a specific size?
Enter the size and unit, choose a file type and click “Create and save test file”. The file is built in the browser and has exactly the number of bytes you entered, which you can verify in your file manager.
Is the test file a real PDF or image?
Yes. PDF, PNG and ZIP are validly built and open normally. The content is a blank page or a single white pixel; the size comes from filler bytes.
Is the file uploaded anywhere?
No. It is created only in your browser and then offered for saving. No server ever sees it.
How large can the file be?
Depending on the type up to 1 GB (PDF, text, zero bytes), 256 MB for random data and 100 MB for PNG and ZIP. Very large files need a lot of memory while they are created.
Why does my system show a slightly different size?
Windows counts 1024 bytes per kilobyte but still calls the unit KB. If you switch on decimal units here, 1 KB equals 1000 bytes; the byte count of the file is exact either way.
Sources and legal basis
- ISO 32000-1 / Adobe PDF Reference – Dateistruktur (Header, Objekte, Querverweistabelle xref, Trailer)
- W3C – Portable Network Graphics (PNG) Specification, chunk structure and CRC-32
- PKWARE – APPNOTE.TXT, .ZIP File Format Specification (Local File Header, Central Directory, End of Central Directory)
- IEC 80000-13 – Binärpräfixe: 1 KiB = 1024 Byte, 1 kB = 1000 Byte
As of: · Editorial policy
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