When sending SMS in Sri Lanka through the text.lk SMS Gateway API, understanding how SMS units are calculated can help you save costs and plan your messages better.
📌 Character Limits per SMS Unit
✅ Sinhala / Tamil (Unicode)
- Up to 70 characters in one SMS.
- If exceeded, message splits into units of 67 characters each.
A single Unicode SMS can contain up to 70 characters. If your message exceeds 70 characters, it will be split into multiple Unicode SMS units. Then, each Unicode SMS unit will contain 67 characters.
Need to learn more about Unicode SMS? Learn more.
✅ English (GSM-7)
- Up to 160 characters in one SMS.
- If exceeded, message splits into units of 153 characters each.
A single GSM-7 SMS can contain up to 160 characters. If your message exceeds 160 characters, it will be split into multiple GSM-7 SMS units. Then, each GSM-7 SMS unit will contain 153 characters.
Need to learn more about GSM-7 SMS? Learn more.
Need to learn more about GSM-7 Extension SMS? Learn more.
🔹 Why Different Limits for GSM-7 and Unicode SMS?
English messages use GSM-7 encoding, which allows 160 characters per unit.
Sinhala & Tamil messages use Unicode (UCS-2) encoding, which takes more data per character, allowing only 70 characters per unit.
Need to learn more about How Text.lk Encodes your messages? Learn more.
🔹 Why the difference Units when Splitting?
When messages are split, some characters are used for formatting, reducing the count per SMS unit.
🔹 How Units Are Counted?
Here are some examples showing how SMS units are calculated on the Text.lk SMS Gateway (Sri Lanka):
Examples:
- English message with 150 characters → 1 unit
- English message with 200 characters → 2 units (153+47)
- Sinhala message with 60 characters → 1 unit
- Sinhala message with 90 characters → 2 units (67+23)
💡 Tips to Reduce SMS Units
- Keep messages short and clear.
- Avoid unnecessary spaces and special characters.
- Test your messages using the text.lk message length calculator.
- For bulk campaigns, try to fit messages into 1 unit.
📌 Tip: Use short messages to save SMS units when sending via a SMS Gateway API (text.lk).
🚀 Send Cost-Effective SMS with text.lk
With text.lk, you can easily send bulk SMS to any network in Sri Lanka using our SMS Gateway API. Whether it’s Sinhala, Tamil or English, our platform ensures fast delivery with real-time reporting.
👉 Start now at text.lk