What is an SMS Segment and How It Works
An SMS segment is like a small box for your text message. When you send a text, your phone puts the message into these boxes. If the message is too big for one box, it gets split into more boxes.
How It Works:
Regular Letters and Numbers (GSM-7):
Most text messages use a system called GSM-7.
GSM-7 is a way of encoding characters that includes common letters (A-Z), numbers (0-9), and some special characters like @, $, and !.
A single SMS segment using GSM-7 can hold up to 160 characters.
✅ Example:
"Hello, how are you?" – Fits in one box.
"Hello, how are you? I hope you’re having a great day and we can catch up soon!" – Too long → Split into two boxes.
Special Characters and Emojis (Unicode):
If you use special characters like emojis 😊 or accented letters (like é), the message switches to Unicode encoding.
Unicode messages take up more space, so each segment can hold only 70 characters.
✅ Example:
"Hi 😊" – Fits in one box.
"Hi 😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊" – Too long → Split into two boxes.
Spaces and Line Breaks Count Too:
Spaces and line breaks (pressing "Enter") count toward the character limit.
A space or line break is treated the same as any other character.
✅ Example with GSM-7:
"Hello, how are you?" – 19 characters including spaces → Fits in one segment.
"Hello, how are you? I hope you’re having a great day and we can catch up soon! Let me know what time works for you." – 149 characters including spaces → Still fits in one segment.
"Hello, how are you? I hope you’re having a great day and we can catch up soon! Let me know what time works for you tomorrow morning!" – 170 characters → Split into two segments (153 + 17).
✅ Example with Unicode:
"Hi 😊 how are you?" – 16 characters including spaces → Fits in one segment.
"Hi 😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊😊 how are you doing today?" – 78 characters → Split into two segments (67 + 11).
Longer Messages Get Split:
If your message is too long, your phone splits it into more boxes.
When this happens, the box size gets a little smaller because your phone adds extra information to keep the boxes in the right order:
GSM-7: 153 characters per box when split.
Unicode: 67 characters per box when split.
Why It Matters:
Even if you see one long message, your phone might send it in three or four boxes (which means more cost).
Spaces, line breaks, and special characters can increase the number of segments — so keeping messages short and simple can save money.