SMS Message Length and Unicode: A Comprehensive Guide
SMS Message Length and Unicode: A Comprehensive Guide
SMS messages are constructed in segments, each at a cost. Understanding the intricacies of SMS length and character sets and how they impact your messaging strategy can save money and enhance your communication effectiveness.The Basics of SMS SegmentationIn most parts of the world, a single SMS segment allows for a maximum of 160 standard GSM characters. This includes spaces between words, which are also counted as characters. It’s important to remember that as your message length increases, so
Reader's guide
This article is organised around the following topics. Use the headings below to scan the existing guidance before reading the detail.
Quick takeaways
- Understanding SMS length and character sets can save money and improve communication.
- In most parts of the world, a single SMS segment allows for a maximum of 160 standard GSM characters.
- Spaces count as characters.
How SMS segments work
Messages are sent in segments. Each segment has a cost. Messages longer than one segment are split into multiple segments.
Modern phones can stitch segments so they appear as one message. That process is called concatenation.
Concatenation and effective limits
Concatenation uses part of each segment for stitching. For standard GSM encoding, seven characters per segment are used for stitching. That reduces the effective per-segment character count for long messages:
- 2 segments: 153 + 153 = 306 characters
- 3 segments: 153 + 153 + 153 = 459 characters
- 4 segments: 153 + 153 + 153 + 153 = 612 characters
Character sets
Standard GSM character set
This includes most Latin letters (A–Z), digits (0–9), and a few special characters like Ö and è. Each of these counts as one character in a segment.
Extended GSM character set
This includes extra characters such as the Euro sign (€) and curly braces ({ }). These characters take two character spaces each in a segment.
Unicode characters
Unicode covers punctuation, mathematical symbols, non-Latin alphabets (for example Thai, Chinese, Arabic), and Emojis. Using any Unicode character switches encoding from GSM to UCS-2. That reduces the single-segment limit from 160 to 70 characters.
When concatenating Unicode messages, three characters per segment are used for stitching. Effective limits for Unicode concatenation:
- 2 segments: 67 + 67 = 134 characters
- 3 segments: 67 + 67 + 67 = 201 characters
- 4 segments: 67 + 67 + 67 + 67 = 268 characters
Emojis
Emojis are Unicode. They reduce the segment length to 70 characters for single-segment messages. Older 16-bit Emojis count as one character. Newer 32-bit Emojis count as two characters.
Unicode alerts
You will receive an alert when a Unicode character is included in your SMS. If you intended the character, ignore the warning. If it was added by accident (for example by copying and pasting from a word processor), remove it in the editor. The alert helps you manage length and cost.
Personalization and Liquid
Personalization fields or Liquid markup change message length. Inserted data varies in length. That affects total character count and segment usage.
Example: "Hey, @FIRSTNAME@."
Contact names differ in length and change the final message size.
Example: personalization affects segments
Consider a message body of 155 characters plus the recipient first name:
- Message to Amar: 155 + 4 = 159 characters (1 segment)
- Message to Charlotte: 155 + 9 = 164 characters (2 segments)
This shows how personalization can change segment count and cost.
Best practices
- Be concise. Keep messages as short as possible while staying clear.
- Know your data. Understand the maximum length of the fields or Liquid markup you use.
- Balance cost and effectiveness. Personalization can increase cost but also improve impact.
Understanding segmentation, character sets, Unicode, and personalization helps you send effective and cost-efficient SMS messages.