A character is not always one SMS unit
GSM-7 supports a defined alphabet. Some characters, including certain braces and the euro sign, use an extension escape and count as two septets. Characters outside the supported alphabet generally require Unicode encoding. Providers can apply their own normalization rules.
Know the common segment limits
A single GSM-7 message commonly allows 160 septets; concatenated messages commonly allow 153 per segment. Unicode commonly allows 70 UTF-16 code units for one message and 67 per concatenated segment. Many emoji use two code units. Segment counts are estimates until confirmed by the sending platform.
Check the final message
Adding a tracking link, sender-related wording or a required opt-out instruction can change the count. Test the exact approved text, not an earlier draft. Arabic, emoji and smart punctuation deserve particular attention.
Use length to improve clarity
Do not remove essential conditions simply to save a segment. Keep one offer and one next step, with a trustworthy destination link. The website SMS counter shows the encoding and estimated segments locally in your browser; it does not send messages.
| Encoding | Single segment | Concatenated segment |
|---|---|---|
| GSM-7 | 160 septets | 153 septets |
| Unicode | 70 UTF-16 units | 67 UTF-16 units |