How to create a dummy file of any size
- Enter the size and unit, or tap a common size such as 1 MB, 10 MB or 1 GB.
- Choose decimal units (1 MB = 1,000,000 bytes, as used by most websites and storage makers) or binary units (1 MiB = 1,048,576 bytes, as shown by Windows).
- Pick a file type. Plain zeros or random bytes are fastest; PDF, PNG, JPEG, ZIP, CSV and JSON files are real, valid files that open normally.
- Press Generate and download. The file is created in your browser and saved straight to your device, exactly the size shown.
What are test files for?
Developers and QA testers use dummy files to check upload limits ("does a 10 MB file get rejected?"), progress bars, timeouts, storage quotas, email attachment limits and file-type validation. IT teams use large random files to measure network and Wi-Fi transfer speeds, and support teams use them to reproduce customer problems. Zeros compress to almost nothing, so if you are testing bandwidth through anything that compresses (zip, HTTP gzip, VPNs), use random data instead.
For typed files, the extra size is added in places that readers are designed to skip: a comment line in a PDF, a private chunk in a PNG, comment segments in a JPEG. So the files pass type checks and open in viewers, while still being the exact number of bytes you need. Nothing is uploaded or downloaded from a server; the file is built from scratch on your device, which is why even a 1 GB file appears quickly.
Is 1 MB 1,000,000 or 1,048,576 bytes?
Both are used. Storage makers and most web services use 1,000,000 (decimal MB); Windows and many developers use 1,048,576 (binary MiB). Choose the one your system expects.
What is the largest file I can create?
Up to 2 GiB. Very large files need enough free memory and disk space on your device.
Will the PDF, PNG and JPEG files open?
Yes. They are valid files with a small label showing their size (very small files get a tiny plain image instead); the padding is invisible to viewers.
Why use random data instead of zeros?
Random data cannot be compressed, so it gives realistic results when testing upload speed, backups or compression.