Understanding the difference between SMS and MMS

Last updated at:

You will learn

Learn how SMS and MMS messages are similar and different as well as when and where to use them. 

SMS marketing is the generic term most people use for marketing using text messages. Technically, though, there are 2 different formats that have distinct capabilities:

  • SMS (short messaging services)
  • MMS (multimedia messaging services).

Similar: consent

MMS and SMS are alike in an important way: consent.

MMS marketing falls under SMS. If someone consents for SMS, it also counts as consent for MMS. If you already have someone’s permission for SMS marketing, you can start sending them MMS messages immediately.

Difference: images and GIFs

What truly makes MMS different from SMS is the ability to include media in the message:

  • SMS can only send text, symbols, and emojis
  • MMS can do the same as SMS as well as include images and GIFs

Messages always start as SMS messages, but adding media instantly transforms it into an MMS message. Examples of media in Klaviyo are listed below:

  • Images, including dynamic images
  • GIFs
  • Virtual contact cards

You will see the image, GIF, or contact card appear in the preview.  

Difference: country availability

SMS with Klaviyo is currently available in the United States, Canada, the United Kingdom, and Australia. 

On the other hand, MMS is more limited. MMS is only available for:

  • All United States numbers
  • Canadian toll-free numbers

Canadian short codes don't offer MMS capabilities, and MMS is not available for mass sending in either the UK or Australia. 

Difference: number of credits

Under Klaviyo's billing plan, the number of credits varies by message type and country. 

US  1 3
Canada 3 5
UK 5 N/A
Australia 4 N/A

This credit system applies all messages sent using Klaviyo, including:

  • Campaigns
  • Flows
  • Conversations

When picking a plan, remember to take into account how many MMS messages you plan to send. 

Difference: character limit

Another thing separating MMS and SMS is the character count.

  • SMS messages can have up to 160 characters
    • 70 with an emoji or special characters
  • MMS messages can have 1600 characters
What counts toward character count?

Everything you put in the message counts toward character count, except for any media. This includes:

  • Text
  • Links
  • Special characters
  • Emojis
  • Variables


How long should SMS and MMS messages be?

A best practice for all text messages is to keep the content short and to the point.

Message type General recommendation Reason
SMS 155 characters Leave a few extra characters so that you don't run up to the 160 character limit, as the estimated count in Klaviyo is not always accurate
MMS 200 characters MMS allows for much longer messages, but typically, you should still try to keep the text short and to the point
Why isn't the estimated character count in Klaviyo exact? 

If you are using shortened links or dynamic content, the exact character count will vary depending on the recipient.

For instance, if you're using the variable to insert someone's first name (i.e., {{ person|lookup:"first_name"|default:'there' }}), the estimated character count is 6. However, if someone's name is Alexandra, the actual count will be 9 characters.


When to use SMS vs. MMS

Use MMS when sending an image or GIF will enhance the message, such as to make it more personal by showing more of your brand. MMS can also be useful for sending out information about a new product, giving you a stage to showcase it visually.

Do not include media for the sole purpose of writing a longer message — most customers do not want to read longer messages or see irrelevant visuals. In these cases, it is better to use an SMS and shorten the content to make it fit into one message.

SMS messages are also better when you want to convey information as quickly as possible. This can be the case if you’re having a flash sale or even for the first message in your welcome series.

Additional resources

Was this article helpful?
50 out of 62 found this helpful