Split a large file

When one file is simply too big

A single file that is too large for an email attachment, too big for a USB stick formatted with an older file system, or bigger than an upload form allows, does not always need to be compressed or shrunk: sometimes the simplest fix is to cut it into smaller pieces that fit, and put it back together at the other end.

How it works

The file is read and cut directly by your browser, in the exact size you set, without loading the whole thing into memory at once, so it works even on files far larger than your device's available RAM. Each part downloads as its own file, numbered in order, such as photo.mp4.part01of12, so you can tell at a glance how many pieces there are and where each one belongs.

Putting it back together

Alongside the parts, a small text file with instructions is downloaded too. On macOS and Linux, the standard cat command joins the parts back into the original file with one line typed in Terminal. On Windows, the built-in copy /b command does the same from Command Prompt. No extra software is needed on either system; both commands are already built in.

What it does not do

This only cuts a file into pieces; it does not compress it, so the parts together add up to the same total size as the original, not less. It does not encrypt or password protect the parts either. To shrink a file's size instead of splitting it, compress an image or a PDF with the dedicated tools on this site, or pack it into a ZIP with the ZIP creator first.