A single Unicode character requires more space (2 bytes) compared to standard GSM encoded characters (1 byte). As a result, the total length of a Unicode message is shorter than a message with standard encoding. A Unicode message can contain up to 70 characters before it must be split into multiple parts.

The limitations for multi-part messages are a little different: a single SMS in a multi-part Unicode message can hold up to 67 characters. The three characters are used up by the information that mobile phones then use to join message parts together in the correct order.