SMS Attachment File Size Limitations

To maintain smooth service and prevent deliverability issues, SMS carriers enforce file size limits. This helps avoid overloading their servers while millions of users worldwide send messages.

Our SMS Attachment Guidelines

We support up to 10 attachments per message, provided the combined size of the message body text and all attachments is under 5 MB.

Carrier File Size Limits

Keep in mind that carriers also impose their own limits. On average, these range from 300 KB to 600 KB, with some tier 1 providers (like AT&T, Verizon, etc.) allowing up to 3.5 MB.

Here are the Carrier Attachment Size limits for some common US Carriers:

The file sizes above will generally be passed along to the wireless carriers. However, due to differences in handsets, file types, and transcoding, we recommend you send attachments no larger than 500KB to ensure the best chance of delivery.

These image file types are supported:

• jpeg
• png
• gif

As of May 2021, there is an issue with Toll-Free MMS file size support; for these numbers, you must ensure that any attachments (including images) are 600kb or smaller.