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How to split a large file into ZIP parts on a Mac
By Himanshu Ranjan · Updated 8 November 2026
Select the file or folder in Finder, open FileDial and choose Archive › Split into ZIP parts… for a custom size, or the 100 MB, 1 GB or 2 GB shortcuts. You get numbered .zip.001, .002 parts in a new folder. It runs offline on your Mac, and your originals stay untouched.
What the tools do
Mail systems and transfer sites cap how big one file can be. FileDial's Archive category has four tools for it: Archive › Split into ZIP parts…, Archive › Split into 2 GB ZIP parts (WeTransfer), Archive › Split into 1 GB ZIP parts and Archive › Split into 100 MB ZIP parts.
They all write numbered .zip.001, .002 and so on, in a new folder. If your selection is smaller than one part, you get a plain ZIP instead of a single numbered part.
Steps
Pick a size below the limit you face, with a margin.
- Select the files or folder in Finder.
- Open the dial with the right Option key and choose Archive.
- Pick a fixed size, or Split into ZIP parts… to choose your own.
- Open the new folder and check the numbered parts.
- Send all the parts, and tell the recipient to keep them together.
The recipient needs to know
Split archives are not as universal as plain ZIPs. The ZIP format supports spanning an archive across files, designed originally for floppy disks and now mainly used for sending parts over email or removable media. But Wikipedia notes that Windows Compressed Folders cannot read or write split archives, so the recipient may need a tool like 7-Zip.
Before sending, tell them to download every part into one folder and open the first. Archive › Deliverable package… adds a README.txt and a SHA-256 manifest inside a ZIP, which helps formal deliveries.
Alternatives that avoid splitting
If one big file is the problem, maybe it can be smaller. Compress video or images first, and for PDFs see our compress PDF guide. If the issue is transfer, AirDrop in the Share category sends to nearby devices without a size cap from an email provider.
For splitting a PDF by pages instead of bytes, see the split PDF guide.
Verify the result
After a transfer, check integrity: Batch › Checksums (SHA-256) writes a text file of checksums, and Developer › Verify checksum… writes a report named OK or MISMATCH. A cryptographic hash lets you confirm the file on the other end is the file you sent.
Choosing the part size
Choose a size under the limit with some headroom, since transfer services and mail systems add overhead. A 2 GB limit calls for parts below 2 GB, which is why Archive › Split into 2 GB ZIP parts (WeTransfer) exists as a preset. For email, 100 MB parts are very small by modern standards, but some mail servers reject far smaller attachments, so check the actual limit of the recipient's provider rather than guessing.
Smaller parts mean more files to send and a greater chance that one goes missing. Larger parts are easier to manage but may hit a limit. If you are unsure, use the custom tool and try a size just under the limit.
- Mail attachments: use Split into ZIP parts… with a size from your provider's stated limit
- Transfer site with a 2 GB cap: Split into 2 GB ZIP parts (WeTransfer)
- Cloud storage with moderate caps: Split into 1 GB ZIP parts
- Very restrictive limits: Split into 100 MB ZIP parts
Common mistakes and when FileDial fits
The recipient puts every .zip.001, .002 and later part into one folder and opens the first with a tool that supports split archives. On Windows, 7-Zip is the common choice; Wikipedia notes that Windows Compressed Folders cannot read split archives. On a Mac, a capable unarchiver app can open the first part. Send these instructions with the files, because a missing part shows up only as an error.
If you control both ends, consider whether splitting is needed at all. Sharing a link from cloud storage, or using AirDrop, avoids the whole job.
It is the right tool when a limit is fixed and the file is truly large, such as a project folder, a set of videos or a disk image. It is overkill when a cloud link would do, and a poor fit when your recipient cannot open split archives.
The simplest choices come first: compress the content properly, use a link, or use AirDrop. Splitting is for the cases where none of those work.
Sending only some parts is the main failure, and the recipient cannot tell until extraction fails. List the parts in your message. Another is renaming parts: the numbers at the end are what ties them together. A third is assuming a split archive opens by double-click on every system. A fourth is picking a part size exactly at the limit, which leaves no margin for overhead.
If the recipient reports an error, ask them to run a checksum on each part and compare; you can produce checksums with Batch › Checksums (SHA-256).
Questions
What are the split files called and where do they go?
The tool writes numbered parts named like .zip.001, .zip.002 and so on into a new folder, as its note describes. If your selection is smaller than one part, you get a plain ZIP instead of a single numbered part, because there is nothing to split.
Can a Windows user open split ZIP parts?
Not with the built-in Compressed Folders feature, which Wikipedia says cannot read split archives. The recipient needs a tool such as 7-Zip. Put every part in one folder and open the first part. It is worth telling them this before you send, because a missing part appears as an error.
How do I check that every part arrived intact?
Before sending, run Batch › Checksums (SHA-256) to write a checksum file. Afterwards the recipient can run a checksum check, or you can use Developer › Verify checksum…, which reports OK or MISMATCH. Developer › Test archive integrity also reports OK or FAILED for an assembled archive.