In most geographical locations around the world, a single SMS segment represents a maximum of 160 standard GSM characters. Spaces between words are also counted as characters. When typing your message, be aware that the longer it gets, the more it costs.
Long SMS messages
SMS messages containing more than 160 standard GSM characters are known as long messages. Smartphone handsets can combine or stitch multiple SMS segments into a single message. This is a concatenated message.
When segments are stitched together, seven characters are sacrificed per segment to help with concatenation. Therefore, the maximum character count for long messages are:
2 message segments: 153+153=306 standard GSM characters
3 message segments: 153+153+153=459 standard GSM characters
4 message segments: 153+153+153+153=612 standard GSM characters
Standard GSM character set
The standard GSM set contains the most widely used characters in everyday language: all Latin characters (A-Z), digits (0-9), plus a few special characters such as Ö and è. For each standard GSM character typed into a message, a single character space is consumed from the SMS segment.
Extended GSM character set
In addition to standard GSM characters, certain characters from the extended GSM character set, such as € and { symbols, can be used in SMS messages. The 160 segment count remains, however these characters use additional space; x2 spaces per character to be exact.
Unicode (non-standard GSM)
Non-standard GSM characters are referred to as Unicode characters. Unicode provides a set of additional characters, including punctuation marks, mathematical symbols, technical symbols, arrows, and characters making up non-Latin alphabets, such as Thai, Chinese, or Arabic script and Emojis.
While Unicode is supported in SMS messaging, be aware that its usage affects your message length.
Introducing a single Unicode character in your message content changes the character encoding to Unicode (UCS-2) and immediately reduces the segment character limit from 160 to 70 characters for a single message.
When messages are stitched together with Unicode characters included, three characters are sacrificed per segment. Therefore:
2 message segments with Unicode: 67+67=134 characters
3 message segments with Unicode: 67+67+67=201 characters
4 message segments with Unicode: 67+67+67+67=268 characters
Using Emoji in your SMS messages
Emoji use is supported in SMS messaging. All Emojis are treated as Unicode characters, reducing message segments to 70 characters. Older 16-bit Emojis count as a single character count and newer 32-bit emojis count as two characters in a message.
Unicode alert
When you include Unicode in your SMS message, you get an alert to let you know there's Unicode in the message. If you meant to include Unicode, you can ignore it, but if you didn’t, you can select the SHOW MORE link. This opens a side panel which shows you what characters are Unicode.
If you included Unicode by accident, such as copying and pasting an apostrophe from Microsoft Word, you can delete this in the editor and replace it and the Unicode alert disappears. You can keep some Unicode–such as emojis–in your message, but they might affect the length and cost of your message.