SMS messages are sent using blocks of characters, called segments -- and segments are how Daisychain calculates SMS usage for billing purposes.
A standard SMS message segment can have 160 "basic characters" -- which includes all standard letters and numbers. There are also "special characters" (like certain accented letters) might actually use up multiple characters in your segment. Emojis use a lot of characters, and change the number of characters allowed per segment in those messages to 70 instead of 160. We know, it's a bit confusing.
Daisychain will automatically do a few things to try to help with segments:
We will automatically combine any incoming multi-segment messages that you might receive into a single message, for easy readability.
We will ensure that any multi-segment messages you send will be encoded in a way that most recipients with modern cell phones will receive them as a single message.
If your message contains a special character that can be easily replaced with a standard character, we'll do that automatically to try to reduce your segment count -- here's a list of those.
When you create an SMS campaign, the message preview will display the number of segments in your message.
If you want to calculate exactly how many segments a message will use (including lots of nerdy details), you can head on over to this SMS segment calculator.