This topic describes the length limit of a Short Message Service (SMS) message and how SMS processes a long message.

SMS message length limit

Note The length limit of an SMS message is determined by character encoding. The maximum size of an SMS message is 1,120 bits or 140 bytes based on international standards.

The length limits of SMS messages in different languages are described as follows:

  • English: 7-bit ASCII encoding is used for English messages. Each message can be up to 140 bytes in length.
  • Other languages: Unicode encoding is used for messages in other languages. Each character occupies 2 bytes of space regardless of full or half width. Each message can be up to 70 characters in length.

Long message processing

The processing methods of SMS messages in different languages are described as follows:

  • English:
    • If you specify no more than 140 bytes in a message, SMS calculates the number of bytes that the message contains as 140 bytes.
    • If you specify more than 140 bytes in a message, SMS separates the message into multiple messages and each message contains 134 bytes.
  • Other languages:
    • If you specify no more than 70 characters in a message, SMS calculates the number of characters that the message contains as 70 characters.
    • If you specify more than 70 characters in a message, SMS processes the message as multiple messages and each message contains 67 characters.

For example, if you send an English message that contains 135 bytes, Alibaba Cloud SMS charges you for using one message. If you send an English message that contains 145 bytes, SMS charges you for using two messages. If you send an English message that contains 269 bytes, SMS charges you for using three messages.