User Manual

SMS Segments & You

The year is 2007. You’re rocking a hot pink Motorola Razr flip phone and your ringtone is Linkin Park, Soulja Boy, or Kelly Clarkson. You text your friend to meet you at the mall, and there’s a small counter at the bottom of the screen, counting down how many characters you have left in your message before it becomes two messages. You ignore it, knowing your mom will yell at you because her “pay-for-each-text” cell phone plan suffers each time you send two messages instead of one. 

That little counter? That’s representative of an SMS Segment. Smartphones have virtually done away with character counters, leading SMS segments to fade out of our collective memory, but the underlying technology behind sending an SMS hasn’t changed. In this article, we’ll go over what you need to know about SMS Segments when marketing via text. 


How Do SMS Segments Work?

There’s a ton of techno-speak behind SMS Segments, but essentially messages are sent in 140-byte chunks known as message segments. Carriers send SMS messages one segment at a time, and message segments are how the SMS industry counts messages. 

When you type letters that go into sending an SMS message, your network provider encodes those characters to transmit the message to your recipient. Your message has a hidden “header” which provides encoding data to the network provider. These messages are encoded in formats such as UCS-2 and GSM-7. 

  • Regular characters (a-z, 0-10 and punctuation) fall under the GSM-7 encoding format

  • Special characters like emoji or smart quotes need to be encoded differently in UCS-2.

Special characters take up more space in the “header” of the message sent to the network. This means fewer characters available for your message before you hit a new “segment” and thus another SMS being sent. 

Next, we’ll go over how all of this works in Drip and what it means for your marketing.


Why Do SMS Segments Matter to Drip SMS?

When you type characters into an SMS message, you use up your allowance of characters in a given segment. Special characters or emojis use even more of your allowance, pushing a message over into additional segments. Each of these segments constitutes a “sent SMS” within Drip and will count as a sent message. If you’re using liquid, this makes things a little more complicated, as your message will likely use up even more characters than you think, as your liquid tags get replaced by real information and dynamic data.

Because of this, your SMS budget could be depleted faster than you might initially think. Drip SMS uses “credits” to show essentially how many segments are left before your budget is depleted. So, if you have four credits left and your abandoned cart text message consists of two segments, you would be able to send two messages before your budget is fully depleted. That’s why it’s important to understand how longer messages could affect your overall usage of Drip SMS.


How Can I Calculate How Many Segments a Message Will Use?

The good news is that our partner, Twilio, has provided a great SMS segment calculator that makes it easy to understand how long your message will be. Check out the calculator

In Twilio’s calculator, you can paste in an emoji to see how that will impact the number of segments in a message.

One caveat is that this SMS calculator will not calculate your dynamic liquid information, just the characters in the tag itself, which isn’t representative of the final text message that will be sent out.