You're smart to ask, particularly because billing is based off message segments.
When you send a text message to your customers – whether it’s “Your order’s ready,” or “Happy Hour this Thursday!” – carriers don’t count just messages, they count segments.
Why? Because SMS is built on older telecom rules, and how many characters you use, and what kind of characters, impacts how many segments your message becomes — which affects cost and deliverability.
The basics
A standard SMS segment in the U.S. allows up to 160 characters when you use only basic characters (letters, numbers, standard punctuation).
If you use “special” characters – like emoji, accented letters (á, ü), or non-Latin alphabets – then the character limit drops (to ~70 characters) because the message uses a different encoding.
When you exceed the single-segment limit, your message splits into multiple segments. So a message of 300 characters might count as 2 or 3 segments.
Every segment counts toward your cost and toward carrier throughput (how many you can send per second). So even if you think you’re sending “one message,” you may actually be sending two or more segments.
Fortunately, we have a segment counter that can watch out for these situations as you're building campaigns. Watch the video below for an explanation of how the segment counter works, and what it is taking into account.
If you haven't already, check out our article on best practices for SMS marketing.