What is the Maximum File Size in FTP Transfers?
By default, there is no technical limit on the maximum file size that you can transfer (download/upload) via FTP, but there are a number of factors that may introduce some artificial limits. In this post, I will talk about what they are.
FTP (File Transfer Protocol) is an alternative method to HTTP (HyperText Transfer Protocol) for connecting to computers and web servers to transfer files. Using an FTP software, free ones would work too, you can easily upload files to your website/server and likewise, download files from your website/server to your computer.
FTP technology does not impose a limit on the number of files and the maximum size of the files for the file transfers, as the developer of FileZilla FTP client states in this comment. What this means is that you can theoretically upload or download files via FTP with an unlimited size. As a side note, I tried uploading a 7+ GB Zip archive and the upload started just fine; neither my hosting server nor the FTP client gave any errors.
Though there is no hard limit on the size of the files you can transfer via FTP, there are a couple of things that may create a limit, allowing you to transfer up to a certain maximum file size. Let's see what these things are now.
Internet Connection Bandwidth Quota
The Internet connection speeds and bandwidths are rapidly increasing around the world but there are still a considerable amount of Internet users -especially mobile phone users- who are on a limited quota in terms of the total bandwidth they can consume in a given month. For this reason, you may not be able to download or upload files larger than a certain value if your Internet data plan has such a limit.
For example, if you have 4GB download limit per month, you will not be able to download a 6GB file as you will have consumed your total bandwidth before the file is fully downloaded.
Network File Transfer Quota
If your computer is a part of a larger network (e.g. work, school, organization, etc.) and if the network administrator have applied limits on file transfers, you will not be able to go beyond those limits. Let's say your network allows you to upload up to a maximum file size of 50MB. In that case, you won't be able to upload a 100MB video file via FTP to your server.
FTP Server File Transfer / Bandwidth Quota
Some server software such as Microsoft's IIS give server admins the ability to configure the FTP server to have file request limits such as maximum allowed content length as explained on this page.
If the server you are connecting to via FTP has such file transfer size limits, again, you will not be able to go beyond them.
FTP Client Limits
I personally haven't come across any FTP client that enforces a maximum file size limit to the transfers but it is a possibility to keep in mind and check the configuration of your client if you stumble upon such a limit and can't figure out the reason otherwise.
FTP Quota Limits
Another thing that controls the maximum file transfer size in FTP is the FTP quota that the server admin can apply to individual FTP users. I explained how it works in detail in our how to set FTP quota for an FTP account tutorial, but basically it applies a limit value in MBs to the total files the FTP user can transfer. For example, by making the FTP quota limit as 200MB, you can assure that the FTP user will not be able to surpass that value in a single file transfer.
TIP: You can also check What is ftpquota? to learn more about how FTP quotas work.
There may also be some other factors that limit the file size of FTP uploads and downloads but the above ones are the major ones that you should consider while transferring large files with FTP.
Also keep in mind that even though there may not be a technical file size limit on FTP transfers, unless you have no other option, it is better to perform your uploads and downloads in parts since with huge file sizes you may experience display, resume and connection issues which may break the transfer process.