Make a test file of an exact size, up to 1 GB, as TXT, BIN, CSV, PDF, JPG, PNG or ZIP
Processed in your browser. Nothing is uploaded. Updated on 24 Oct 2026.A dummy file generator makes a file of an exact size for testing uploads, limits and transfers. Choose TXT, BIN, CSV, PDF, JPG, PNG or ZIP and any size from 1 byte to 1 GB (1,073,741,824 bytes); the file is written on your device, byte-exact, and nothing is uploaded.
Choose the file type: TXT, BIN, CSV, PDF, JPG, PNG or ZIP.
Tap a common size such as 1 MB or 10 MB, or type any size in bytes, KB, MB or GB, up to 1 GB.
Read the line under the choices: it says what the file really is and the smallest size that type can be.
Press Make file. Large files are written to disk as they are made, with progress and a Cancel button.
The Dummy File Generator makes a file of exactly the size you ask for, so you can check what an upload form, an email server or an API does at its limit. Ask for 5 MB and you get 5,242,880 bytes, not "about 5 MB". KB, MB and GB here count in 1,024s, as Windows and most upload limits do; under More options you can switch to 1,000s.
Every file is a valid file of its type, padded to size. It is not a document, a photo or a dataset with meaning.
| Type | What is inside | Smallest size |
|---|---|---|
| TXT | One readable line, repeated | 1 byte |
| BIN | Zeros, or random bytes | 1 byte |
| CSV | A header and numbered rows of Test Users at example.com | 65 bytes |
| One A4 page saying it is a dummy; padding in a stream no page draws | 850 bytes | |
| JPG | A 16 x 16 grey image; padding in comment segments | 163 bytes |
| PNG | A 16 x 16 grey image; padding in a text chunk | 360 bytes |
| ZIP | One uncompressed entry, dummy.txt | 116 bytes |
There is no MP4 option on purpose: a padded MP4 would play as nothing, and calling it a video would mislead the test.
The file is written to disk while it is made, in 8 MB pieces. On Chrome and Edge on a computer you choose where to save it and the pieces go straight there. Elsewhere they go to the browser's private storage on disk, then download from it; only a browser with neither keeps the pieces in memory, and the page says so before a large file. Progress is shown and Cancel stops at once.
Zeros compress to almost nothing, so a transfer or a zip can make them look faster than real data. Random bytes come from your browser's cryptographic source and do not compress, which makes them the fair choice for speed tests.
Choose a type such as PDF or TXT, tap a common size like 1 MB or type any size in bytes, KB, MB or GB, and press Make file. The file is written on your device and is exactly the size asked for, down to the byte, up to 1 GB.
By default 1 MB is 1,048,576 bytes and 1 KB is 1,024 bytes, the way Windows and most upload limits count. Under More options you can switch to decimal units, where 1 MB is 1,000,000 bytes, as macOS and disk makers count.
Yes. Each one is a valid file of its type: the PDF opens as one A4 page saying it is a dummy, and the JPG and PNG show a small 16 x 16 grey square. The extra size is padding stored where readers skip it, so the files open quickly.
A TXT or BIN file can be 1 byte. A ZIP needs 116 bytes, a JPG 163, a PNG 360 and a PDF 850, because each format has a fixed structure before any padding. A CSV needs 65 bytes for its header and one row. Smaller sizes are refused with the minimum stated.
Usually yes. The file is written to disk in 8 MB pieces as it is made, either to the place you choose or to the browser's private storage, so memory use stays small. A phone needs 1 GB of free space, and the progress bar and Cancel button stay on screen.
A video padded to size would not play as a video, so offering one would make an upload test pass for the wrong reason. To test a video upload, record a short clip with your phone and trim or join it to the size you need with the video tools on this site.
Still stuck? Ask about Dummy File Generator and anybody who knows can answer. No account needed.
Same job, other tools: Blank Image Generator – Download a plain image in one solid colour, or transparent, at any width and height · Sample Image Download – Sample JPG, PNG or WebP files at fixed sizes, with the exact byte count, for upload tests · Compress Image to 100 KB – Get any photo under 100 KB for forms and portals · Compress Image to 1 MB – Trim a high resolution photo to just under 1 MB.
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