Email Attachment Size Limit: How to Send Large Files via Email

Most email services can send files up to 20 MB without a problem. If you need to send something larger than that, upload the file to a cloud storage service first, then forward a link to that file via your email instead of attaching the file directly.

Many email servers refuse to accept email attachments over a certain size. While attachment sizes haven’t kept up with the times, there are other easy ways to send someone large files over email.

Table of Contents

What's the Maximum Size of an Email Attachment?
Use a Cloud Storage Service to Send Large Files Over Email
Create and Send Multi-Part Archives
Use a Large-File Sending Service

What’s the Maximum Size of an Email Attachment?

In theory, there’s no limit to the amount of data you can attach to an email. Email standards don’t specify any sort of size limit. In practice, most email servers—and some email clients—enforce their own size limits. In most cases, email attachments can be up to 20 MB or so in size.

Gmail allows you to attach up to 25MB to a single email, but this is only guaranteed to work if you’re emailing other Gmail users. As soon as the email leaves Gmail’s servers, it could be rejected by another email server. The maximum file size on Outlook is only 20 MB. When sending messages over these services, they will automatically give you a helping hand and suggest alternatives—such as using Google Drive for Gmail attachments and OneDrive for Outlook.com.

It’s not even as simple as looking at the maximum attachment size of the service you use and the service you’re emailing—emails often travel over several mail transfer agents when they’re sent, so you may have your attachment rejected by a server along the way if you attach too much data, though this is not often a problem anymore.

You should also bear in mind that email attachments are generally MIME encoded, which increases their size by about 33%. So 10 MB of files on your disk will become about 13 MB of data when attached to an email.

Use a Cloud Storage Service to Send Large Files Over Email

Your simplest option is to store files you want to share on a cloud storage service like Dropbox, Google Drive, or OneDrive. You can then share the file with someone and inform them via email that you have done so. They can then click a link and download the file directly to their computer.

If you use Gmail or Outlook.com, you’ll find that Google and Microsoft have integrated Google Drive and OneDrive into their respective email services. Just click the Google Drive or OneDrive button when sending an email, and you’ll be able to share a file via email. Gmail and Outlook will walk you through choosing a file that already exists in your cloud storage drive or uploading a new file.

 

This is the option many email providers are pushing us towards—if you try to attach a large file in Gmail or Outlook, you’ll be prompted to upload it to Google Drive or OneDrive first. 

Outlook.com’s user interface is more compact but offers all of the same functionality.

 

If you use something like Dropbox, you can share the file from the cloud storage service’s website. For example, right-click a file on Dropbox’s website and select “Share link” if you use Dropbox. If you have the Dropbox app installed on your computer, you can also right-click any file in your Dropbox folder, and you’ll see a “Share” command there, too. Every major cloud storage provider out there offers this kind of functionality, and it is the most reliable way to share large files.

Create and Send Multi-Part Archives

If you’re looking for a more traditional, do-it-yourself method, you can split your file up into smaller parts. For example, if you had a 50MB file you wanted to email—or even a collection of large files—you could use a file compression program like 7-Zip to create an archive, and then split the archive into five 10MB pieces.

 

After splitting the archive, you can then attach all the separated pieces to separate emails. The recipient will need to download each attachment, and then use a file extraction program to extract the larger, complete file from the separate archives.

While it can be a bit cumbersome, this traditional method still works as well as it always did. Some recipients might be confused by the separate attachments—or at least won’t enjoy jumping through hoops to reassemble them. If you’re not sure whether your recipient will know how to do this, it’s probably better to choose an easier method.

Use a Large-File Sending Service

To help answer the large attachment problems, a number of file-sending services have sprung up online over the years. These services let you upload a file, and then give you a link to your upload. You can then paste that link into an email and the recipient can click the link and download the file.

Of course, these services have to make money somehow. They may do that by displaying ads, limiting the maximum file size available to free users, or demanding a subscription fee. We’ve covered many of these online services for sending and sharing large files before. And note that when you use an online service, you’re entrusting it with your files. That may be okay if your files aren’t particularly sensitive, but you’ll probably want to shy away from uploading sensitive data to a free service you haven’t heard of before. Of course, you could encrypt the files before uploading them — but that would add additional hassle for the recipient, too.

These file-sending services work fine, so long as you’re okay with whatever ads or limitations exist, and you understand the risks—especially with sensitive files. However, we typically recommend just using a cloud storage service instead.